There's nothing wrong with going to two different vets, Maria...in fact, that could be a good thing if and when you need a second opinion to already have a "stand-by" vet familiar with your cats.
Just use vet #1 most of the time because he charges you less, is more personable, etc. and because he's so thorough, and use vet #2 only if vet #1 won't give you prednisone since he charges you more and is not as personable. (I think I got that right.... did I? I'm in the edit screen and I can't look back at your messages to review.)