never house 2 males uros together, even females may fight each other, because uromastyx aren't particularly social. It would be best for the lizards to be set up by themselves unless breeding.
With that said how big is your lizard and how much floor space does your cage have?
A 40 gal breeder will only hold ONE adult uromastyx happily. I have a small boy in a 30 gallon now, he'll get a 40 gal once one of my snakes moves up to something bigger. Your best bet would be to stick with one, if you're not going to breed, you dont need another! They are interesting characters with awesome personalities, one will be a handful enough. Definitely do your research, they need a LOT of heat and fresh vegetables every day. Good luck!