Bearded Dragon UV lighting

Question
Is it possible to over expose my beardies to UV lighting? I have a 6 foot long by 18" wide aquarium. My beardies are only a few months old. I have four of them in the aquarium. Two greys and two sunburst dragons. I currently have two Repti-Sun 10.0 flourescent UV bulbs that extend the length of the tank. I presently have a non UV emitting 75 watt head bulb. I bought a laser temp gun. With my current setup I can only reach a ground temp of 110 degrees a few inches from the light. So i recently purchased a mercury vapor UV and heat lamp which i haven't received yet. My question is, is that too much UV for the dragons. In total I will have a TRex Mercury Vapor UV emitting bulb along with two 36" flourescent Repti-sun 10.0 bulbs that extend the length of the tank. Would it be better to use one UV bulb on the side of the tank that doesn't have the heat lamp and to just use the heat lamp on the other side? Are the repti-sun 10.0 too much UV by themselves? My tank is pretty high i think it is over 18". I appreciate all of your help.  

Answer
 The amount of UVB produced by the Reptisuns is great but no where near the amount produced by the sun.  I wouldn't go for mercury vapor without a UVB meter.  What you have is good as long as they all can get within 8 inches of it.  Frankly, I'm not a fan of the T-Rex MV bulb.  I prefer the Westron Mega-ray.
 110F is rather warm. 100-105F is the optimum temp for a basking spot.
 Before they are 5 months old, make sure you only have one male in there, and that they are all unrelated.  If you hold the beardie with his/her tummy in your palm, butt end facing you, lift the tail straight up.  Above the vent, on the base of the tail there will either be one bulge, which is a female, and two bulges with a dimple in between would mean a male.