Repunched Mint Mark?

Split plating. That happens a lot on the 80's cents. The lower left corner get's split and the zinc rot sets in.

I check a RPM book and nothing is listed that would look like that. With the number of years from then to now, it is were a RPM, other examples would have been found. No such reports. A very large percentage of these coins are found. Because of the adding the mint mark to the dies, there was a fin that developed from the punching. This punching split the planchets until the fin wore down. Later die states were the ones that didn't have this problem. It is just a matter of time for the zinc to start to work. The 1990 is when they started adding it to the master die as part of the design. But even a pin jerk can affect the zinc under neath. (Note the recess on the 1990 between the 1 & 9?)

Split plating leads to zinc rot so it is generally a bad thing to have on a coin.

Thanks for everyone's input. I'll chalk this one up to an "almost found something cool" :)