That is a contemporary counterfeit. Back in the early 1990’s I bought a genuine 16-D and a 42/41 to fill the last two slots in that book I had been assembling since the 1970’s… The dealer was a buddy of mine and I knew he had this counterfeit dime. I wanted the genuine 16-D slabbed but didn’t want the hole in my book so I twisted his arm to make the fake dime part of the deal……… It is very well done. The D was added then it looks like the counterfeiter carried it around in his pocket to make the D wear down and look right. I am not one to laud a counterfeiters work, but this guy was good!
oh wow I'd never have been able to tell the difference. When time comes I'll buy a genuine certified one although I've heard some of them are fake as well.