I have not seen any but I do know as a coin hobbyist that we see many tampered coins with 2 heads or 3 tails on them. Some people think they are mint errors but they are not. Its impossible for the mint to make that error given their manufacturing process. The 2 sided coins are made by machining 2 other coins in half and then combining them. I guess someone could do that with a metal coin centers as well (same principle as a coin) and then place it back in the chip. I do not know how good it would look when complete but its certainly possible to do it.