The hot stamped ones are fakes. They were made to sell into the hobby as old chips.
They were sold into the hobby and fooled several collectors including *****, nah I won't tell his name.
There is a sale thread then an apology thread in the archives.
I found out by accident after I saw them in NY. Chipco confirmed they had made them a few months earlier.
I have 4 denoms. I think there was one more color.