I haven't even seen the word "codepage" used in many, many years.. my best guess is that, if it's coming from the registry now, you might have different access rights, one of the machines can't read it, and reverts to a built-in default.. but that's really just a guess..
as usual, my suggestion is to go to
Home - Paradox Community, where the long-time Paradox users still hang out.. there are several international groups there, but there are only a handful of PdoxDOS users left..