Iguana Reptile Glo 5.0 and 2.0 (Compact)?

I was wondering is it completely necessary to use Reptile Glo 5.0 and 2.0, the 2.0 has a higher visual light output than the 5.0 and is the reason they tell you to use both, i am interested in 5.0 because of the UVB UVA waves which are emmited from the bulb, i would prefer to use only the 5.0 due to the fact i do not wish to over load my circuit by having 3 heat/light lamps, any ideas or tips on both subjects?