~~~ or something the casino did.

This was a practice (shaved) with BG, same as they did with some plaques as well back prior to the introduction of their samples inventory with Eiffel Tower and details though, they did have a few with fictitious names such as "Casino Int'l" and similar.

Sometimes it's the only way you can find an issue; especially one that has been destroyed which, was not uncommon back when. I have UK documentation showing where hundreds of thousands of chips were destroyed, per casino, and in some cases I have the sole survivor sent to me by head of security who were in charge of destruction. Not saying this is one, though, or if it's even rare or scarce because it's not in ChipGuide; as there are thousands of chips not found in the guide which are are known.