The baseplate has the same, single version of the lettering. After the initial mould-blowing, then a second (accidental) impression is made while the glass is still malleable: probably while the mould was opening, the vase was lifted very (very!) slightly then returned to the baseplate. It would all happen so quickly (they were banging them out), the blower probably didn't even notice. Either that, or the vase was twisted slightly before the mould was opened, but then the mould lines may become slightly 'smeared'.
Final offering: the vase was returned to the mould for some reason. Perhaps some minor, but noticeable, imperfection?
All hypothetical, of course, but unless we can ask George, we'll never know...
