Whoops, missed that this was answered!
Interestingly, I was playing (not dming- very rare) in a 'pick up' game tonight, and we had this come up. The dm said one save ends both and I took his word for it.
But where does it specify? Have I just overlooked the blindingly obvious somewhere?
Edit: Although Donatello's reasoning seems perfectly sound, on reflection. Never mind. It prolly doesn't really need to be spelled out, per se; each "save ends" clause is one saving throw.