'96D 5c copperwsh?

It has either been:

1) Plated; or
2) Exposed to something that ate the nickel away from the surface, but left the copper.

It can be hard to tell which, as if you scratch the surface of either deep enough, it should show "silver" cupronickel underneath (although the former tends to be smoother under the loupe than the latter).

I have several of these in my unusual PMD collection.