DEFDAM - Definitely Damaged How? Only the person who altered the Obverse would know how it was done. Welcome to Cointalk
I'm not saying your coin is this, but i don't think the doubleing at the top of the words Independace Hall is Post mint damage. JMO. https://www.error-ref.com/incomplete-punch/
I think that the coin was used as a shim under a table or chair leg. The stuff on the REv is from that side being on the floor when the table/chair moved.
Looks damaged to me. Like it was placed in a vise with another Kennedy Half Dollar on it, wrapped to protect it against the vise grips and tightened until it left what you are seeing. Any doubling is the result of the vice and didn’t occur until after the coin was in circulation.
What is it with these guys looking for errors? Most of them don't even collect coins. Are they just naive? Are they just looking for attention? Are they looking for money? What's the motivation? That's all I'm asking. What an unproductive waste of time all that is. That's all I'm saying.
It’s all about how much they can sell it for. Way too many ads about finding error coins in your change that are worth thousands. In reality only a couple have every been found.
An incomplete punch "clip" would be evident on both sides. It's not the case on the Kennedy Half in question. Also, his face is distorted. It shouldn't be.
I disagree that an incomplete punch will be evident on both sides. Since the punch is from only one side there is every chance that a punch cycle that was interrupted (as in the machine was stopped) could cause an indention on one side only.
This half dollar is an in-collar double strike with a low-pressure indent on the second strike. Minimum die clearance during the second strike was greater than the thickness of a half dollar, which is why the area beyond the indent wasn't struck by the dies -- an "invisible strike" in other words. I'm not sure what the low, short ridges on the obverse next to the indent were caused by.
The mate for this coin would naturally be an off-center half dollar with an unexpanded, low-pressure brockage of the obverse design on its reverse face.