Thank you @perf12, and @Germania for your suggestions and thank very much @peter for your efforts! This was very valuable information for me. (I am sorry for my extreme late reply)
If my source is correct, the Forgery 1 should be "[...] 3/4 mm shorter and have a longer top inscription."
(
https://www.anglo-indian-affairs.co...-Reprint.pdf ).
It seems that the design frame on the suspected F1 specimens is smaller than on the presumed originals, although I'm not yet sure whether this also relates to the spacing between the frame and the perforation lines. The top inscriptions are indeed longer, but so are the bottom inscriptions.
If I get another Bundi material in the future, I'll take a closer look at all of these details again. Your theory seems very plausible to me. Thank you very much for pointing this out!
In the meantime, I'll do some more research into the different printings, paper types that were used. The Indian Feudatory States are a philaletic paradise. I love it! hehehe