My gray tree frog used to hibernate on me every year, granted our house was cool, but nowhere near what it was outside. I don't actually know if it is required that they do this or not, but given that one is acting strangely and the other is not I would be concerned. What kind of soil is in the potted plant? If you haven't already, I'd change out that soil for pure, no fertilizer peat moss, or sterilized leaf litter compost. You may also want to turn the heat up a bit to wake up the sleepy froggie, so she can fatten again, and then turn it down so they can sleep. And yes, get tested for parasites, just so you can rule that out for sure. Hopefully some others with more experience will comment, good luck!