Vocal Tag Team

Pretty much Exactly What It Says on the Tin, a Vocal Tag Team is a band/musical act which features two (or more) lead singers, rather than the more typical singular vocalist. The singers may trade off vocals on a song-by-song or even a verse-by-verse basis, or they may just harmonize constantly. Particularly common, if not ubiquitous, in musical duos and vocal groups. If more than one member of a band is a songwriter, the band member who wrote the song is usually the one who sings lead on it.

Note that this doesn't apply if one particular singer is clearly signposted as the "lead" singer and the other(s) merely backing vocals. Only if all singers involved get to handle genuine lead vocal chores (or if the harmonizing is truly constant) do you have a Vocal Tag Team.

There can be any number of reasons to do this. The various singers may have vastly differing vocal styles which fit into one song type or another. It may be simply for the sake of variety, or to give one singer a bit of a rest. It may be an effort to appease egos, or to avert Face of the Band. Or, if the band features a male and a female singer, they can engage in Silly Love Duets.

For a former backing singer (or a non-singing instrumentalist) suddenly getting lead vocal chores, see Step Up to the Microphone. Compare Soprano and Gravel.

Country

 * Lady Antebellum (Hillary Scott and Charles Kelley). Dave Haywood is the Garfunkel.
 * Alison Krauss & Union Station (Alison Krauss, Dan Tyminski, sometimes Ron Block).
 * The Bellamy Brothers (Howard and David Bellamy) split the vocals about 50/50.
 * So does Montgomery Gentry, usually by giving Eddie Montgomery the verses and Troy Gentry the chorus.
 * Joey + Rory (husband and wife duo, Rory Lee Feek and Joey Martin Feek) split the vocals, although Joey has gotten all the singles so far.
 * Steel Magnolia usually has Joshua Scott Jones sing the first verse and Meghan Linsey the second verse.
 * Dave & Sugar alternated the lead vocals between Dave Rowland and the "Sugar" (a revolving door of two female backing vocalists).
 * Little Big Town gives Karen Fairchild about half of the lead vocals, and splits the rest among the other three members (Jimi Westbrook, Philip Sweet, Kimberly Schlapman). All four of them split the lead on "Boondocks".
 * Little Texas (Brady Seals, Tim Rushlow). After Brady left in 1995, Jeff Huskins replaced him on keyboard, but not on co-lead vocals.
 * Lonestar started out with Richie McDonald and John Rich as co-lead vocalists, although only one single with Rich on lead vocal got released. (And even then, it was on the charts at the same time that then-labelmate Mindy McCready released a duet with McDonald.) John Rich was fired from the band in 1998 and went on to form Big & Rich, in which he would alternate with "Big" Kenny Alphin on lead vocal, even though Rich only got lead vocal on two singles out of eleven.
 * Thompson Square (husband and wife duo, Kiefer and Shawna Thompson)
 * Gloriana (Mike Gossin, Tom Gossin, Rachel Reinert, also Cheyenne Kimball until she left)
 * Even though Duane Allen is considered the lead singer of The Oak Ridge Boys, the other three (tenor Joe Bonsall, baritone William Lee Golden and Basso Profundo Richard Sterban) have gotten their turn on lead. Notably, all four trade the lead vocal on "American Made" and "You're the One".
 * However, this was mostly averted when Steve Sanders replaced Golden in the late 80s-early 90s, as Steve took lead on nearly everything but "True Heart" in that timespan.
 * The Lost Trailers originally alternated between Ryder Lee and Stokes Nielson, but upon moving to BNA Records, Lee became the sole lead singer. The band then broke up, but Stokes promptly re-established it as a duo with new lead vocalist Jason Wyatt.

Electronic

 * Animal Collective splits their vocals pretty evenly between Panda Bear and Avey Tare.

Pop

 * Animotion (various, but always a male + female lead)
 * The B 52s (Fred Schneider, Cindy Wilson and Kate Pierson)
 * The Bangles (all four of them) And, for the record, they were not able to avert Face of the Band by doing this.
 * The Beach Boys. Each of the five members of the "classic" lineup (Brian/Carl/Dennis Wilson, Mike Love, Al Jardine) sang lead on at least one Top 20 hit.
 * The Bee Gees
 * The Free Design.
 * Most modern Boy Bands and Girl Groups do this: Backstreet Boys, New Kids on the Block, The Spice Girls, Wilson Phillips etc.
 * The Spice Girls: their songs often sound like a prolonged instance of Finishing Each Others' Sentences.
 * Hanson. All three brothers sometimes take lead vocals, though 2007's "Go" is their only single to date that doesn't feature Taylor singing lead.
 * Human League (Philip Oakey, Joanne Catherall and Susan Ann Sulley)
 * The Hush Sound (Bob Morris and Greta Salpeter)
 * The Monkees
 * Roxette (Marie Fredriksson and Per Gessle)
 * Scissor Sisters: Jake Shears and Ana Matronic
 * Simon and Garfunkel
 * Sonny And Cher
 * Starland Vocal Band
 * McFly (Tom Fletcher and Danny Jones)
 * Three Dog Night featured three vocalists (Danny Hutton, Chuck Negron, Cory Wells) backed by a band.
 * Tally Hall (Rob Cantor, Joe Hawley and Zubin Sedghi) Andrew Horowitz gets to Step Up to the Microphone at least once per album.

R&B/Soul

 * The Everly Brothers
 * Hall And Oates (although John Oates' songs rarely make singles)
 * The Righteous Brothers
 * Sam and Dave
 * The Temptations (David Ruffin and Eddie Kendrick switched off as lead singers on many of their biggest hits, with gritty baritone and falsetto voices, respectively. The post-David Ruffin hit "I Can't Get Next To You" featured all five of the then-members of the group singing lead.)

Rap/Hip-Hop

 * EPMD took tag-team rapping to an art form.
 * M.O.P. do this quite a bit too. Clearly this is a recurring theme among rap duos with initialized names.
 * "As We Enter" by Nas and Damian Marley features some sweet old-school style tag-team rapping/toasting.

Rock/Metal

 * 311
 * Alice in Chains- Jerry Cantrell and Layne Staley originally, now William Duvall
 * The Band (Rick Danko, Levon Helm and Richard Manuel. Robbie Robertson wrote most of the songs but only sang a handful of parts.)
 * Barenaked Ladies (Steven Page and Ed Robertson -- until Page left, but Kevin Hearn has taken duties on several Page vocals since then)
 * The Beatles (all four of them)
 * Blink 182 (Mark Hoppus and Tom DeLonge)
 * Blonde Redhead's Misery is a Butterfly. The two vocalists, female Kazu Makino and male Amadeo Pace, alternate between tracks -- Kazu is the only vocalist on the first track, Amadeo is the only one on the second, Kazu is the only one on the third, and so on...until the tenth track, "Pink Love" -- the climax of the album. Amadeo starts as the lone vocalist, for the verse, and then Kazu comes in to sing the chorus. They keep alternating within the song.
 * The Blood Brothers - Jordan Blilie and Johnny Whitney switch back and forth constantly, also switching between screaming and singing cleanly. There are only two songs in their catalogue where each singer has a "solo moment"; for Jordan, this song is "Johnny Ripper", and for Johnny, this is "Nausea Shreds Yr Head."
 * The Blue Oyster Cult saw two equally talented performers, Eric Bloom and Donald "Buck Dharma" Roeser not only trading lead and rhythm guitar, but also alternating lead vocal between them. (While Eric and Buck did 80% of BOC vocals, it's fair to say the other three core members all got a go too, so there were perhaps three reserve members of the tag-team)
 * Caedmon's Call - Cliff Young is the most prominent vocalist and has racked up the most lead vocals over the year, but his wife Danielle Young has taken more and more vocal leads over the years, to the point where half of Raising Up the Dead features her on lead vocals. Derek Webb has had almost as many leads as Cliff during his time with the band, and Andrew Osenga took Derek's place during his absence, with the two getting lead vocals a few times on the same album when Derek returned for Overdressed.
 * The Cars (Ric Ocasek and Ben Orr)
 * Chicago: Initially the vocals were shared between Peter Cetera (tenor) and Terry Kath and Robert Lamm (baritones). Kath died and Cetera left, and they were replaced by Bill Champlin and Jason Scheff respectively.
 * Cold Chisel had Jimmy Barnes as its frontman, but effectively had a second lead singer in guitarist Ian Moss -- the former's screaming vocals contrasted nicely with the latter's more melodic tones. Many songs were either sung by Moss (e.g. "My Baby", "Saturday Night") or began with Moss singing and had Barnes take over halfway through (e.g. "Bow River", "When the War is Over").
 * Crosby Stills And Nash (and Young)
 * Damn Yankees (Ted Nugent, Jack Blades and Tommy Shaw)
 * Taking a cue from its forebearers, Styx (Tommy Shaw and Dennis DeYoung) and Night Ranger (Jack Blades and Kelly Keagy)
 * Eagles (pretty much all of them, at one point or another, but mostly Don Henley and Glenn Frey)
 * Everything Else (Matt Morley and Sam Black, both members of the duo)
 * Fleetwood Mac (Lindsay Buckingham, Stevie Nicks and Christine McVie)
 * Girlyman
 * Goo Goo Dolls have John Rzeznik (their recognized frontman) and Robby Takac. Takac actually handled the majority of the lead vocal duties before Rzeznik's voice caught the attention of record producers and he was asked to Step Up to the Microphone.
 * Grand Funk Railroad (Don Brewer and Mark Farner)
 * Guster (Adam Gardner and Ryan Miller)
 * Heart (Ann and Nancy Wilson)
 * Heidevolk, almost everything is sung by both singers.
 * House of Heroes trades off between Tim Skipper and A. J. Babcock to the point where it's hard to tell who's who.
 * (Jefferson) Starship (Mickey Thomas and Grace Slick)
 * Jefferson Airplane too, but the team was Grace Slick and Marty Balin.
 * Journey (Steve Perry and Greg Rolie, though Perry sang lead exclusively when Rolie left).
 * Kiss (Paul Stanley and Gene Simmons, and occasionally Ace and Peter as well)
 * The Libertines (Carl Barât and Pete Doherty)
 * Linkin Park (Chester Bennington and Mike Shinoda)
 * The Mamas And The Papas
 * Maximum the Hormone has got Daisuke (lead singer), Ryo (guitarist) and Nao (drummer) sharing the lead vocals on almost every of their song, using the mix of their respectively hardore, rock, and female J-pop sounding voice as part of their style. Ue-chan, the bassist, can also be heard on a few songs, and generally sings backing vocals.
 * Mike + The Mechanics (Paul Carrack and Paul Young)
 * My Bloody Valentine had Bilinda Butcher and Kevin Shields
 * Nelson (Matt and Gunnar)
 * Nine Days (you remember, Absolutely (Story Of A Girl)?) did this, but nobody knows it because neither of their two singles had the second vocalist on lead.
 * The New Pornographers. Carl Newman handles most of the leads, but Neko Case, Dan Bejar, and more recently Kathryn Calder have been getting their fair share of leads on each album. Plus there are several choruses on which they're all singing in unison without a distinct "lead". This is befitting their Supergroup nature.
 * Oasis (Liam and Noel Gallagher, though only the former sings in their first album)
 * Paper Route's lead vocals were shared by T. J. Daly and Andy Smith, until Smith left in 2010.
 * Pink Floyd (Roger Waters and David Gilmour; in the early days, Syd Barrett; sometimes, Richard Wright)
 * Queen largely fits this trope; while Freddie Mercury was the band's nominal singer, everyone except John Deacon sang lead occasionally (although Deacon did write some of their most popular songs like "You're My Best Friend" and "Another One Bites the Dust").
 * Showbread was this, prior to Ivory Mobley's departure. Ivory and Josh Dies would trade off rapid-fire vocals within the same song, frequently alternating lines within the same verse.
 * Sister Hazel has Ken Block and Drew Copeland as their lead singers. While Ken sings most of the lead vocals, Drew has at least one song per album (except the first) where he sings lead instead.
 * Slot (Daria "Nookie" Stavrovich and Igor "Cache" Lobanov, with similarities to Chester/Mike of Linkin Park. Nookie does the singing, Cache takes care of the rapping while both of them have been known to share the screaming duties on occasion; for example, they both scream at least once on Ангел OK / My Angel)
 * Indie rock band Stars; technically male vocalist Torquil Campbell is moreso the lead singer than the female vocalist, guitarist Amy Millan, but both do sing frequently and their duets tend to be among the band's more famous songs.
 * Supertramp, in the beginning, had co-lead singers in Rick Davies and Roger Hodgson, often on the same song ("School"; "Fool's Overture"; "Rudy"). Richard Palmer-James was also tagged in for a couple of songs on their debut album and a cover of "All Along the Watchtower" during his tenure.
 * 10CC (all 4 members of the original lineup).
 * The Who, with at times both lead singer Roger Daltrey and guitarist Pete Townshend singing. John Entwhistle and Keith Moon did backing vocals and at times did a full song.
 * They Might Be Giants: Linnell and Flansburgh get about the same number of leads, as well as plenty of harmony and backing parts with themselves and each other. Sometimes they'll even tag-team on different versions of the same song.
 * Brazilian band Titãs is an extreme case: in the early days, out of the 9 members, 6 were singers. Currently, there are 3 (out of 4, not counting the hired drummer).
 * Status Quo alternate between Francis Rossi and Rick Parfitt on lead vocal depending on the song; when bassist Alan Lancaster was in the group he too took lead vocal on some songs.
 * The Mk3 line-up of Deep Purple were known for this; although David Coverdale was the designated frontman, bassist Glenn Hughes took lead on several songs and in some cases they alternated within the same song (e.g. Burn, Sail Away)
 * Similarly to the Deep Purple example, Yes did this with Jon Anderson and Trevor Rabin during the latter's tenure in the band.
 * For their first few albums, The Lemonheads split songwriting and vocal duties between Evan Dando and Ben Deily. Deily left the band after this, and eventually Dando basically was The Lemonheads.
 * Sonic Youth, with Thurston Moore and Kim Gordon sharing vocal duties and Lee Ranaldo contributing vocals one or two songs per album.
 * X: John Doe and Exene Cervenka share vocals on half the songs and split solo lead vocals on the rest.
 * Super Time Pilot - for most of their lone album Did We Happen To Begin?, Rob Potylo and Nikki Dessingue either harmonize or trade off verses. The exceptions are four tracks where Nikki sings alone, and one where Rob does. Oh, and far from using the male/female vocals for silly little love duets, they spend many songs acting like type 2 vitriolic best buds, for humor's sake.
 * In Fugazi, Ian MacKaye and Guy Picciotto generally divide vocal duties evenly.
 * Stereolab. While Lætitia Sadier handled lead vocals and Mary Hansen handled backing vocals, they harmonized and played off each other so often that it was widely considered a defining feature of Stereolab's sound. That is, until Mary Hansen's death in 2002.
 * XTC: Andy Partridge handled most of the vocals, but Colin Moulding sang lead on the songs he wrote.
 * Straylight Run (their earlier works) had a brother/sister duo by John and Michelle Nolan. John was primarily the lead vocalist with Michelle providing backup or harmonizing vocals but they do have a few songs where Michelle sings lead ("Now It's Done", "Tool Sheds and Hot Tubs", "I Don't Want This Anymore").
 * Indie band The XX: (Romy Madley Croft/Jamie Smith)
 * Basically all incarnations of Sebadoh did this, even though Lou Barlow was still widely considered the Face of the Band: Early albums had him splitting singing and songwriting with Eric Gaffney, later albums (after Gaffney left) had him splitting it with Jason Lowenstein, and a few albums in the middle had him sharing vocal turns with both.
 * The Halo Benders' songs usually have Calvin Johnson and Doug Marstch singing at once: A lot of their first album God Don't Make No Junk even had them both singing entirely different melodies and lyrics over the same music.
 * The Runaways: Joan Jett and Cherie Currie.
 * Regardless of whether the official lead singer is Bobby Kimball or Joseph Williams, Toto albums often featured songs where the lead vocals were either shared or performed exclusively by David Paich and Steve Lukather (and, more rarely, Steve Porcaro).
 * Lacuna Coil Andrea Ferro and Cristina Scabbia, Female Male contrasting vocals.
 * Heatmiser: Neil Gust and Elliott Smith.
 * The Velvet Underground had shared vocal duties between Lou Reed and Nico on their debut, and between Lou and Doug Yule on their last two, with additional guest spots for John Cale and Maureen Tucker.

Fictional

 * In the original Knight Rider episode "Let It Be Me", Michael joins a rock group with his former lover Stevie. The band, being a direct analogue to Fleetwood Mac, features both of them singing.
 * In the Special Edition of Return of the Jedi, Jabba The Hutt's house band acquires a second vocalist for Sy Snootles to play off of.
 * Finch and Christie from Chartbreak
 * In the manga Beck, the eponymous band's lead singers are Chiba, who's influenced by hip-hop and punk, and Koyuki, who's more suited to ballads.

Unsorted

 * Chas 'n' Dave's novelty song "Rabbit, Rabbit" features rapid-fire lyrical handoffs between Chas and (you guessed it) Dave. Later covered on TV by The Two Ronnies, to thunderous applaause.
 * Yuki Kajiura's band Kalafina (Keiko, Wakana, Hikaru, and formerly Maya). It is awesome.
 * Folk-rock/children's music duo Trout Fishing in America splits vocals about 50/50 between Keith Grimwood and Ezra Idlet, although Ezra usually does the ballads.
 * Japanese punk band/theater troupe Strawberry Song Orchestra features a male harsh vocalist trading off and overlapping with a soprano singer and an alto.
 * Matt Morley and Sam Black are both lead singers for Everything Else.
 * MOVE (Japanese electro/Eurobeat group) features the rapping of Motsu and the singing of Yuri in most of their songs.
 * Non-music example: Jason and Randy Sklar frequently switch in and out during their routine. Often finishing each others sentences, talking over one another, and speaking in unison for comedic effect.