neon tree dragons

[Starforce2]

http://www.generalexotics.com/lizards/agamids-for-sale/dragon-agama

I was finaly able to find their latin name, however, I notice at petco they house several in the same cage..and before I get any I'd like to know how to tell them apart. Anyone know how to sex these?

 

[Starforce2]

I thought there was people here who had these? I've read an article about sexing but I still can't see any difference between all the ones I've seen so far.