Here's an example of both types of antique inlaid poker chips. One with a diecut symbol, one with an inverse diecut symbol. It would appear that they save the leftover pieces from the inverse to make the classic diecut chip.

But how do they keep the "loose pieces" in the right position in the press? There is no connection to the white material inside the first C on the pink chip. On the brown chip, there's no problem as the inside of the C is just the brown chip behind the inlay.

I'll bet RobertE knows the answer.