I am new to error coins and I have run across a few that I can't seem to find an explanation for. 1. A coin that looks like it has two rims at one part of the coin. 2. A quarter that has a black semi circle imprinted on the front and the back of the coin and if I put another quarter in the semi-circle it fits perfectly back and front. There are no other imprints left just those. 3 I found a quarter with a blob of a mint mark and it looks like there is a dent encircling the mint mark is this from being repunched? IF someone could please give me some schooling that would be nice..lol thank you for your advice in advance.
