Is it OK to use overlapping control ids within window/dialog if there's a visibility condition that's blocking them being visible at the same time?
As long as there's only one visible at any time I think it's fine, in fact I've done it myself, but I'd wait for an expert answer.
It's fine. But you probably shouldn't do it with fixed control id's, also in some scripts you could get problems.
also don´t do that with viewtype control IDs.
Last time I tried it also effects navigation depending on how they get hidden ie hiding the group and not the actual control