Ray was right!! (SPOILER!)
Ray was right - Beckwith really was Marzin, in a sense! The same actor played both parts although they seemed to have different eye colors and Marzin had a bigger nose.
Ray did say that Marzin could have had plastic surgery and eye contacts or something. I think the actor was fitted with prosthetics for the role of Marzin. Also, I think the actor's real eye color is blue. Beckwith had a different accent, too - I think he had more of an American accent. The same actor is listed in the credits on IMDb for both parts.