Different Proteus

Interesting. Based on the production date code on the bottom, they were both produced in factory E only five days apart in 2008, and the one with the added text is the older one and it doesn't look like the die was retooled, so I would conjecture that it is indeed related to tooling marks that look to be inside the indent - they probably either had two sets of metal molds or one larger mold that could make two boiler pieces at once (the numbers trace the pieces back to the machine so if some start failing quality control they know exactly which section of which machine the part came from) and for whatever reason die 1 did not have this text but die 2 did. I'll have to check if mine came from slot 1 or 2 next time I'm in storage. There could have been even more toolings, if other people's Proteuses (Proteusi?) have other number marks, but it seems like they probably wouldn't have bothered to buy more of the expensive toolings for a minor character like that