Every so often someone proposes this (and sometimes someone who thinks they are clever actually carries it out) and it's always a terrible idea. The purpose of peer review is not to uncover fraud. It's not even to make sure what's in the paper is correct. The purpose of peer review is just to make sure what's in the paper is plausible and sane, and worth being presented to a wider audience. The purpose is to weed out obvious low-quality material such as perpetual motion machines or people who are duplicating other's work as their own. Could you get fraudulent papers accepted in a journal? Of course. A scientist sufficiently knowledgeable of their field could definitely fool almost any arbitrarily rigorous peer review procedure. Does fraud exist in the scientific world? Of course it does. Peer review is just one of the many mechanisms that serve to uncover it. Real review of one's work begins after peer review is over and the work is examined by the scientific community at large.