Early BudJones coin inlay chips did use a process that applied black ink or paint to the design on the coin. I believe this only lasted for a year or two. You will see this on chips from Desert Inn, Frontier, and others.

I had never noticed it on a chip with brass colored coins, just the silver colored ones. The Chip Rack doesn't list all the chips that exist in both versions; I don't see it for your Colorado Belle for instance. It's hard to be sure that's what we are seeing here... you really need to see the chips in person.

You might bring it to the next Convention and let AllanM look at these closely. I suspect he will end up giving the black-letter chip a new TCR number.