how to manage the case where only one file differs per branch

[omeldoid]

hello, i've decided to finally start using cvs and it happend with a
particular project in mind. i'm working on a web-related project,
where i have to test changes locally on my personal computer and then
publish them on a different server for the web. now my problem is,
that i have to manage two sets of certain variables, such as, for
instance, at least local and remote usernames and passwords.

what is the right approach? should the two scenarios be considered as
two branches? but if only one file (which contains the sensitive data)
is tagged, i'd have to use the -f switch of update, if i'm not
mistaken, but exactly how?

help appreciated, thanks a lot,
andrej.