Nope not too much, and remember your dealing with radiation. a 5.0 is the min, and only good for 18". Based on the wrong knowledge you would think that installing 2 5.0 would hurt them, or a 10.0, or the arcadia 6% + reflector that put out literally 10x the radiation as a 5.0 without a reflector would be roasting chams alive. The only uv that can hurt a cham is the bad batch of CF bulbs from 5 years ago, or a way wrong setup Merc vapor unit.
PS: i assume you have leaves in the cage that the cham can hide in. Chams regulate uv like they do heat. in a 4ft cage the bottom 18" have almost no uv even with the high output arcadias.