Nope - don't leave both amps hooked up. If only that you might inadvertantly, in a time of relative stupidity or intoxication, turn them both on at the same time. Be safe and stay happy.
Get some banana plugs and run 2 sets of speaker wires, one from each amp. Then you can just plug and play the one you want to use at the time. That's what I do when I feel the need for tubes over solid state, and visa versa.
Enjoy,
Bob