Separated at birth

 
[The actors Michael Gough and Benedict Cumberbatch.]

Also separated at birth
Nicholson Baker and Lawrence Ferlinghetti : Ted Berrigan and C. Everett Koop : John Davis Chandler and Steve Buscemi : Ray Collins and Mississippi John Hurt : Broderick Crawford and Vladimir Nabokov : Ted Cruz and Joe McCarthy : Jacques Derrida, Peter Falk, and William Hopper : Elaine Hansen (of Davey and Goliath) and Blanche Lincoln : Harriet Sansom Harris and Phoebe Nicholls : Ton Koopman and Oliver Sacks : Steve Lacy and Myron McCormick : Fredric March and Tobey Maguire : Michael A. Monahan and William H. Macy