Thanks guys for your help. I've yet to relay this to the roofer, but
the question remains "what to do?". He claims that he has combined
the two before and has not had an incident in twenty years since he
originally did it. That case was a galvanized drip edge meeting
copper gutters. It's somewhat of a conundrum, because we'd really
love to have the more aesthically pleasing look of copper, but don't
want to risk roof discolration or having to replace the flashing
again. Option A might be to just get rid of the galvanized all
together, but that would open the door to a lot of carpentry and
painting work for new siding (not to mention cost!).

I don't want to put anyone on the spot, but would you recommend to
just flash new galvanized steel over the old galvanized product?