I'm sorry, but I just don't see how your point about 'exists' is at all relevant. I think we're all agreed that declaring the same var twice in the same scope is a mistake - that's why "warnings" throws that error after all - and there's no counterpart to anything like that in using 'exists'.
I guess I'm looking at this from some unique perspective, then - well, except for all the other languages that consider double-declaration like this a fatal flaw. Fair enough; this thing that is considered a critically-bad programming practice elsewhere is not considered as such in Perl. Got it.
Thanks very much to all those who have contributed useful and relevant information.
I hate storms, but calms undermine my spirits.
-- Bernard Moitessier, "The Long Way"