Yeah, an issue with temps was the first thing I could think of besides being sexed properly. I would imagine it would be pretty hard to get them not to breed, even if you kept them together all the time and stressed them out.
Just as a frame of reference. I keep my breeding females hot side at 88 and the cool side at 75, these are constant 24/7 temps. Last year I let it drop to 70, but ended up with RI in a couple snakes, this year I have it at 75 and have no issues with them breeding. You may be keeping them too hot. If they can't thermoregulate to cooler temperatures I would imagine that they would have issues building/getting ready for eggs. Maybe even cause them to reabsorb eggs if they do get that far?