Once again, posting for a friend. He found this and sent me pictures and it kind of reminded me of the coin in the incomplete clip thread that was going. Anyone have comments:
I think the radius of the "damage" line is greater than the radius of a cent, therefore I don't think it is a clip. Unless it ended up in a nickel or quarter clipping doohickey.
I can see how it could resemble an incomplete clip, but due to the uneveness and roughness, I think it's corrosion related. I would expect a partial punch have a smooth, distinct line https://www.error-ref.com/incomplete-punch/
I think it looks like a zinc cent so than would be the best curved blisters I’ve ever seen for plating bubbles.
I believe it is a platting issue. As the blanks went through their copper bath, it was sandwiches between others that caused the anomaly. Just my thoughts.