Only one type of forgeries is known to me. It was produced immediately after the WWII and it is so poor that can only confuse those that did not see the originals.
The differences are visible at a first glance: different typography was used, text is narrowed and the relationship between overprinted elements is quite different. The most obvious distinction is invalid type of coat-of-arms. The originals have coat-of-arms of the Banovina of Croatian, while forgeries have coat-of-arms of the Independent State of Croatia (different sequence of white and black squares).
Original on the left and forgery on the right.
