Sorry I took so long to respond. I have been unable to log in for three days. Here is what I wanted to send:
Thanks for your observation, and I am not an expert on these stamps either. From what I can gather from stamps for sale and stamps with expertized certificates (one of those sold apparently yesterday. I made a bid on it, but the stamp then disappeared. It has a certificate and was similar to mine.
Also, see https://www.ebay.com/itm/383414389091?chn=ps
This one is currently for sale and is about the worst I have seen.
I would not try to sell my stamp without first getting a certificate of authenticity. This is an easy one to forge: a cheap Turkish stamp with a black overprint. I have seen dozens that have been off, but they all seem to sell just fine, and for decent prices. Also, there are dozens I have seen that are much worse than mine but are cancelled, which means they have gone through the postal systeme okay.
But you are quite correct in your observation. But I am not sure that means that it isn't what it purports to be. Also, I acquired this stamp about 20 years ago, when prices for it were much lower.
Finally, you are also correct that the font on the "1" in the sttamp that you showed is different from the "1" on my stamp. That could be troubling, but from what I can tell. The font used on my stamp for "1" is also used on other stamps. E.G..: https://www.ebay.com/itm/3245600905...494521700617