I used to work at a games studio that would get these delivered fairly regularly, usually paired with a particular motherboard and presumably a custom BIOS.
I think we were technically supposed to return them but the manufacturers never enforced it, so once the chip was actually released to the public - and assuming the sample was stable enough for general use - the PC would rotate into normal stock and eventually get sold for cheap to staff or end up in the spare parts bin.
While it was cool at first to get pre-production chips before anyone else, it became pretty mundane and I'm not at all surprised to see them out in the wild decades later. Interesting piece of history though!