If you were planning to house them together, I would plan some time to keep them seperated at least in the beginning to give the new addition a sufficient quarantine period. Also I would be sure you have a girl, and get another girl. I would not plan on housing a pair together. Also........yes they should be approx. the same size. There are some different sites online that you can see pictures that would show differences in males and females but ..........looking at them from the rear..........holding up their tail slightly, and looking for either one bulge to the rear of their vent(female), or two bulges(male). Hard to explain, and its hard to tell on some dragons. Where are you located? Maybe someone here lives close to you and could take a look at the dragon to sex it? Chris