The Case of Mr. Pelham Alfred Hitchcock Presents : Season 1 Episode 10

Someone is impersonating Albert Pelham. Mr. Pelham thinks that his life is being taken over by the doubles life. Pelham decides to take action against the double. He changes his bank signature. Unfortunately, the double manages to duplicate it. Finally, at his apartment Pelham is able to confront his double. The false Pelham insists that he is the real one. Pelham becomes almost convinced and goes insane.