This has been discussed before on-line, and I know there are a couple of chippers convinced there are two varieties of this chip.

The pic below shows two sides of the same chip. In my opinion, this is a question of fading of the pink color in the chip, not two chips manufactured differently. The pink plastic chip of similar construction used at the Caribe Hilton in Puerto Rico also exhibits this change in color. It gets almost white after time.

DonL