Great find!!! Over here (S. Korea) we have the same problem with our non-holed coins......and some of the holed coins. But, the holed coins seem to come out of the ground in better shape, though almost always older, then the non-holed coins. The
ground minerization eats into the face of the coin, and we end up seeing a coin with "coin rot."
A great looking coin. Hope you find a bunch more.