As leo's are mostly nocturnal you don't really need a basking lamp - in their natural habitat they gather heat from the ground. I think you should put a few more hides into the viv with a bit of greenery as cover (plastic plants). I also don't recommend housing a male and female leo together unless your going to be breeding and unless the female has enough energy reserves to sustain growing eggs inside her.
A few q's:
- Are you using any kind of thermostat? If so, what stat on what piece of heating equipment?
- What are the temps your getting on both the cool side and the warm side?
- How old are they both?
- What are you feeding them? How much/how often
- How long have you had them?