We haven't had any females that like each other's company very well. We housed two sisters together since we bought them as babies and everything went well up until the 5 month mark. One would lay on top of the other one all the time (a sign of dominance) and shot up in size. They were feed independently so food was not a factor, yet one was taking over. She started showing her beard and bobbing at the other one, making the second girl wave and run away. Once we separated them, the second one caught up and is apparently much happier being without her sister.
Sibling rivalry isn't just for humans, you know!
A dragon can become a bully overnight, especially around the time they hit "puberty". Keep an eye on them and make sure you monitor their lengths and weights to ensure there isn't a dominance issue starting.
A couple of websites that give examples of determining sex:
http://www.beardeddragon.org/articles/sexing/
http://www.dachiu.com/sexing.html
http://www.faunaclassifieds.com/foru...ad.php?t=90679
If in any case, try and take some pictures and we could help you out!