I ran into this issue with two different vending machines this past weekend with a particular ¥500 coin. I thought it was because the coin was pretty tarnished

I ran into this issue with two different vending machines this past weekend with a particular ¥500 coin. I thought it was because the coin was pretty tarnished in one spot - but I just checked and sure enough it is one of the new coins. Apparently this has been an issue for a while now, and fairly common, but this is the first time that I can recall running into it.