My son has a 1.5 yr old bearded dragon and decided to get another one, the new one is about half the size of the older one. Is it safe to put them together after the quarantine period?
He had put the new one in a little plastic aquarium and sat it inside of the aquarium of the other one, the older one sat beside it bobbing up and down. If he holds one up beside the others aquarium the bigger one flares out and opens his mouth.
Dragons can be VERY AGGRESSIVE AND TERRITORIAL. It's not uncommon to end up with dragons that are missing toes or the end of their tail for this reason. Extreme caution should be used.
Very good that you have them separated right now especially considering the size difference. The bobbing etc is in fact the aggression coming out. They need to establish the hierarchy and determine which one is the boss.
If they are male/female then there's a much better chance that they'll be able to get along but it's still VERY RISKY since the male may chase the female all over the place. Two males can be far more dangerous. Two females probably have the best chance of being ok.
A "Breeding Pair" is usually established when they are both tiny and have grown up together. It also usually means One Male with more than one female.
It's usually best to place dragons together when they are both extremely young. Once older they tend not to handle new comers very well but that's not to say it can't happen. Just introduce them slowly and be sure to keep a close eye on them. There's no way to know for sure if they'll handle it well.