When Wally tears up the note to pass out his IOUs, he takes out a rubber stamp. Dink asks Wally what the stamp is. Wally responds and tells him it is a stamp with his signature. But at 11:52 when you see the stamp, it only stamps his name, not his signature.
Near the end when the pieces of the paper are laid out together in proper sequence, it's clear they do not actually fit together and if they were torn from the same sheet, they were not originally in that order.