Today is is my last day at Sundance — I have three more screenings to go, including a “sneak preview” of Steven Soderbergh’s “The Girlfriend Experience” before I fly home first thing tomorrow — so I have to write quickly. You wouldn’t think Michael Cera and Paul Giamatti would have a whole lot of common except they’re both actors with movies here, but interestingly they both play “themselves” in their respective films. Giamatti’s movie “Cold Souls,” in the dramatic compeition, is a funny, dark metaphysical comedy in the Charlie Kaufman mold, with the actor having his soul temporarily extracted so he can better cope with the rigors of playing the title role in a stage production of “Uncle Vanya.” The problem is that Giamatti’s soul ends up with international traffickers, and he travels to Russia to try and get his soul back from a soap actress. Cera plays himself in the quirky “Paper Hearts,” a mock documentary, also in the dramatic competition, about his real-life girlfriend Charlyne Yi (she also plays “herself”) and her search for love, and how the process of making the documentary complicates their budding on-screen relationship, which Yi (a standup comic, musician and sometimes actress) and the director (who is played by an actor) insists was entirely scripted. At a Q & A, Cera claimed he wasn’t playing “himself” but “someone who has the same name as me.”