I found a 1917 S penny with two depressed dots on the obverse(almost looks like someone took a nail punch to it) I wasn't sure if it was post mint damage or not but then found a 1945 Lincoln cent with what looks like the exact same punch pattern.
Lastly, found another 1917 penny with a depressed diamond pattern on the obverse and reverse and not sure what to make of it.
Second, yes good question to ask when you see multiple coins with the same issues. Those circular depressions are most likely from the coins being used as target practice, but as you note there are also some hand tools which could cause similar damage. The diamond-shaped depressions in that '17 Cent were caused by someone squeezing the coin in the textured jaws of a machinist's vise.
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