Bearded dragons fighting + head bobbing please help!?

I have 3 bearded dragons 1 adult,and 2 sub adultsthe adult lives by himself and the other 2 live in a 60 gallon. The 2 sub adults used to live in the same cage untl I came home 1 day to see the smaller 1 hand was bleeding and he\she couldn't walk on it so I split the cage in half so they wouldn't be able to injure eachother again but yesterday I gave both of them a bath and they were getting along just fne so I thought maybe they could live together again so I took out the seperator and put both of them in the same 60 galon cage and the larger ones beard turned black and puffed up then he started bobbing his head while the smaller one just sarted waving his\her arms then the larger 1 chased the smaller 1 around the cage trying to bite the smaller 1 I'm not sure what sex\gender they are but they keep doing the same thing larger one gets black beard and smaller 1 sits and waves then the larger 1 chases him\her wha does this mean are they fighting or trying to mate I'm scared to put them back in the same cage somebody help