Temperature control for 2 carboys in 1 refrigerator?

I'd like to increase my brewing frequency but keep fermentation temperature control a high priority. I have a refrigerator and two-stage controller for heating/cooling for a single vessel currently. My refrigerator has room for two carboys, but I realize the two vessels are going to be fermenting at different temperatures even with a shared ambient temperature. I wanted to do something like keep the refrigerator running and then run a separate heating pad or wrap for each carboy and maybe then I'd be able to ferment one at 65F and another one at 70F for instance.

Does anybody have experience with this? Recommendations or warnings?

Off topic but what two stage temp control unit are you using?

Ranco Two Stage.