If the other dragons are smaller than your dragon, then yes he'll probably keep doing that. As they all grow up and get to be around the same size though, he may knock it off.
Beardies often see smaller lizards (including other beardies!) as a snack, not as a friend or playmate. They're solitary creatures and shouldn't be living together, even if they are the same size. If you don't have a lot of room for their three separate tanks, there are some pretty nifty stands out there that allow you to "stack" the vivs. But don't keep them together. Here's an awesome thread on cohabitation in case you haven't seen it already -
viewtopic.php?f=6&t=154908&hilit=cohabitation
They should especially be kept separate when you have a male and a female, because the male will literally mate the female to death, whether her body can survive egg-laying or not. Two males will be aggressive with each other and one may get bullied or killed, and two females will bully/kill as well.
You have a long while until you'll need to worry about breeding though, since your dragons are still youngun's! :wink: Females need to be a minimum of two years old before it's safe to breed them. For now, focus on making sure your babies are getting plenty of good food and UVB and water and supplements and lighting so that they can grow up to be happy and healthy.
And this one is a good sort of "checklist" to make sure you know what you're getting into with breeding!
viewtopic.php?f=4&t=126455. There's a lot of good points in there that most people may not consider. Also, before you breed please double check the genetics of your dragons. Talk to the breeder you got them from, or if you got your dragons from a pet store, ask them which breeders they buy from. Inbreeding is unhealthy and irresponsibly, but luckily it's avoidable!