I have two lizards but?

I don't know if they are the same breed of lizard. When i first bought my first lizard, i bought it as an Iguana, but it didn't grow to look like one. It looks like a water Dragon. Then i added another Iguana and this one really looks like an Iguana. The first ones head is more rounded and the body is more petite and bright greenish blue turquoise colored. The second one has a longer but narrower head and is dull in color like most Iggy's i've seen. But they get along very well for 4 months now and they eat together in peace. But my question is how can i tell if it is a water Dragon? And if it is will they continue to get along. I have compared the pics from the internet and it looks just like the water dragon.