I think the explanation is just fine. And the Possible sample/ prototype is a Good way of describing it and shouldn’t be called unknown just because you don’t have documentation and not put in the chip guide.
Especially when it was obviously made as one with the same image as the others used. They may never have been shipped to the ship, club or casino but were made as an example for the owner and manufacturer to decide if they wanted them.
I’m no expert on this subject but I think your idea of discarding such chips without documentation is wrong.
Should we take all chips out of the guide that say Attributed also ? It at least gives us an idea what the chip might possibly be or is until proven otherwise.
Just my opinion
Thanks
Torrey