Just what I need to to confuse me more doing some research I found this article now I have to be double careful or actually triple careful didn't know that a MD could be a double die alsohttps://www.ngccoin.com/news/article/5688/Double-Dies-vs-Machine-Doubling/
Willy, I think you misread the article, as it can't be for coins with the multiple hubbing process mentioned at the top of the article. What the article didn't mention is the tidal wave of Single squeeze coins that attributers call DD, but since there was no possible doubling of a second hubbing ( since there was no second hubbing), it is due to a mechanical process after the single hubbing. They say that it is recoil or something similar that causes the Doubling and thus is a DD, I do not agree, but that be as it may. Since TPG grades some of the SS modern stuff as DD, it may be acceptable to the modern collectors. Jim
Willy I think it's cool that you are spending time and trying to educate yourself, that's how we learn it's a tough hobby just about the time I think I'm getting it right I make a mistake and get it wrong. Keep learning.LOL Dave
As I read the article it pretty well explains the difference between doubled dies and mechanical doubling. It does also explain that a doubled die coin can also exhibit mechanical doubling at the same time. Any coin can show mechanical doubling if there is movement of the die during striking. If a doubled die moves during striking, then yes the resulting doubled die coin can also exhibit mechanical doubling.