They actually don't even need to beable to see eachother...they are pretty amazingly smart little creatures and know they are there even without seeing them. Not all will still communicate when they can't see another yet one is there...but I find that more do than don't in my house. My beardies can not see each other yet only one doesn't partake in the conversations so to speak.
When one can see another because they are out roaming it's not uncommon for the more dominate male to head bob the other and go psychotic in his viv...while the less dominate one could very well arm wave and give the little head bobs which almost look like a female does.
Head bobs, black beards, an arm waves can't be used to tell the sex of a beardie.
Have you tried to sex your beardies yourself?
http://www.beardeddragon.org/articles/sexing/
If you are still confused as to what they are you could post a pic
with their tails positioned like in the pic in that link and we would
be happy to try and help.