Martian Memorandum Spoiler

Dr. Lawrence Barkley says "A man came to me 20 years ago for appearance-altering surgery. That man is now Marshall Alexander".

Then after ransacking Big Dick's safe, Tex's notebook comes up and he says, "I know Collier Stanton became Marshall Alexander".

Did I miss something? Did he just assume that the man who came to Dr. Barkley was Collier Stanton because of the 20-years-ago coincidence?