What's the story with some atomisers having engravings saying "Tilemahos" and some don't?
the story is, there are different versions with different engravings.
in the picture you see from left to right v1, v2 and v2+ (x1 springomizer have the same engravings)
v1 has "tilemahos" and "gg" engravings on the base, no engravings on the tank
v2 has "gg" engraved on the base, no engravings on the tank
v2+ and x1 has no engravings on the base and the eagle on the tank.
and as you see in your picture, you can combine the different parts
for further information, watch the wiki page
Overview RTA - GG Wiki
Tilemahos V1, V2 + V2+