One of these stamps is a genuine stamp and the other(s) is a forgery. Can you tell the difference? If you are having trouble, see the "hints" and answer below.
Genuine - the corners are not joined. The "f" and "i" in Oficial are joined, perf 12; Forgery - the corners are joined. The "f" and "i" in Oficial are seperated, perf 11 1/2