When you tune in to I Know This Much Is True on HBO this Sunday, no need to adjust your sets: There really are two Mark Ruffalos on your screen.

In the limited series based on the best-selling novel of the same name by Wally Lamb written and directed by Blue Valentine auteur Derek Cianfrance, the Avengers star takes on the intense task of playing identical twins Dominick and Thomas Birdsey in what the network describes as "a family saga that follows their parallel lives in an epic story of betrayal, sacrifice and forgiveness.

While playing two characters in one project sounds difficult enough, Ruffalo's job here also requires him to sensitively tackle the portrayal of severe mental illness as Thomas suffers from paranoid schizophrenia. No easy feat, but if he pulls it off, prepare to hear his name come this year's Emmys. (If they even happen, that is.)

Ruffalo's hardly the first actor who's tackled playing twins, however. In fact, it's become something of a rite of passage in Hollywood. To see all the stars who've come before him, scroll down!

Stars Playing Twins, Mark Ruffalo, Lisa Kudrow, Lindsay Lohan, Leonardo DiCaprio

Warner Bros; HBO; Shutterstock; Melissa Herwitt/E! Illustration

Freddie Highmore, The Spiderwick Chronicles, Stars Playing Twins

Nickelodeon Movies/Kobal/Shutterstock

Sarah Paulson, American Horror Story Freak Show, Stars Playing Twins

FX

Mireille Enos, Big Love, Stars Playing Twins

HBO

Jason Sudeikis, Eastbound & Down, Stars Playing Twins

Fred Norris/HBO

Jackie Chan, Twin Dragons, Stars Playing Twins

Distant Horizons/Media Asia

Bette Midler, Lily Tomlin, Big Business, Stars Playing Twins

Touchstone Pictures

Jean-Claude Van Damme, Double Impact, Stars Playing Twins

Snap/Shutterstock

Vanessa Hudgens, The Princess Switch

Netflix

James Franco, The Deuce

HBO

Mark Ruffalo, I Know This Much Is True

HBO

Yael Grobglas, Jane the Virgin, TV Double Duty

The CW

Alexandra Chando, The Lying Game, TV Double Duty

ABC Family

Troian Bellisario, Pretty Little Liars, TV Double Duty

Freeform

Sarah Michelle Gellar, Ringer, TV Double Duty

The CW

Lindsay Lohan, The Parent Trap, 90s Breakout Roles, Twins

Disney Enterprises

Ewan McGregor, Fargo, Twins

Matthias Clamer/FX

Armie Hammer, The Social Network, Twins

Columbia/TriStar

Mike Myers, Austin Powers, Twins

New Line Cinema

Lisa Kudrow, Friends, Twins

NBC

Adam Sandler, Jack and Jill, Twins

Columbia Pictures

Dove Cameron, Liv and Maddie

Tony Rivetti/Disney Channel

Yasmine Al Massri, Quantico, Twins

ABC

The Man in the Iron Mask, Leonardo DiCaprio, Twins

United Artist

Jeffrey Tambor, Arrested Development, Twins

Fox

Adaptation, Nicolas Cage, Twins

Columbia Pictures

The Prestige, Christian Bale, Twins

Buena Vista Pictures

Edward Norton, Leaves in the Grass, Twins

Telepathic Studios

Legend, Tom Hardy, Twins

Universal Pictures

Paul Dano There Will Be Blood, Twins

Paramount Vantage

Chris Rock, Bad Company, Twins

Touchstone Picture

Matt Lucas, Alice in Wonderland, Twins

Disney Pictures

Tatiana Maslany, Orphan Black, Twins

BBC America

Bette Davis, Dead Ringer, Twins

Warner Bros.

Jennette McCurdy, iCarly, Twins

Nickelodeon

Sam Underwood, The Following, Twins

FOX

James Carpinello, The Punisher, Twins

Lions Gate Films

Eddie Murphy, Bowfinger, Twins

Universal Pictures

Sam Worthington, Avatar, Twins

20th Century Fox

Hayley Mills, The Parent Trap, Twins

Walt Disney Pictures

Jeremy Irons, Dead Ringers, Twins

Twentieth Century Fox Film Corporation

I Know This Much Is True premieres Sunday, May 10 at 9 p.m. on HBO.

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