Hey guys! I'm going through my first ever half dollar box and I found something weird. As I have been told before, I know that "Weird does not mean valuable." But I might as well just post this. Is this just damage or what?
My best guess is that you are looking at Abrasion doubling. Notice the heavy die polish in the fields.
Actually Paddyman has it right. The abrasion doubling has been "debunked" Here is a reference for abrasion doubling. https://www.error-ref.com/?s=abrasion+doubling
After 1989 the MM were added to the working hub and not the individual dies. So, rpm's cannot happen. What you have is mechanical/machine doubling.
I'll tell you why people get so confused, it's because they call it "machine doubling." Well which machine are we talking about? It's a very nondescript term. Instead call it "strike doubling." Now we're getting someplace. It's a consequence of the striking of the coin. Something slipped, moved, ever so slightly, causing the distortion.
Here it is on the mint mark of a 1968-S cent. It's all over that date, for that matter. Whether these mint marks were "punched" (the proper term) into the die as in the older days or not they're as prone to strike doubling as any area on the coin. We can differentiate the "re-punched marks" (RPMs, which do happen to be collectable), we can tell whether or not the secondary image is due to the strike. You can get more on that here: https://doubleddie.com/58243.html. See photo from link of die-sinker at work below photo of coin).
