Here's an image of the stamps in this design from romaniastamps.com:



The author is cautious about whether individual stamps are genuine given the number of forgeries but I think it's still useful to see them as a group.

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I have images of genuine overprints. From Nigel's set, at least half are forgeries. (The first "T" of "PTT" the halves of the top bar are equal in length. The left half of the bar should be longer.)

There are other characteristics, but on none of the two images is the overprint clear enough to take a closer look.

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