He is not a puppydog …. he's perfectly happy having an entire viv all to himself with daily periods of freerange fun time on the floor , visits from his pet human/s.
If you get another dragon , DON"T get another male ,get a female BUT unless you intend mating/breeding them, never let them be together.
It's OK to have another dragon in the house / room so long the two aren't forced to cohabit in the same tank or even be forced to see each other all day and night (very stressful).
(This applies even if it's large tank (unless you are dedicating an entire room (5m x 10m say ,and there are multiple basking spots, feeding stations and hides and the two can get away from each other)).
It can be very charming watching a male beardie trying to woo a female beardie by head bobbying and sporting a
blackbeard, and her response which can be either giving him the cold shoulder, or doing armwaves and slow pressups and back at him.
But it's best they only see each other occasionally and are never allowed to physically meet.
A larger dragon is fully capable of killing a smaller dragon (and an adult is more likely to see a hatchling as snack)).