"They're in a 33gallon (soon to be replaced) and are fed sprouts and crickets regularly. And he eats just as much as his big brother(sister?). Any thoughts?"
First thing..for dragons that are nearly a year old...they are in way too small tank. I had one single dragon out of her 35 gal tank since she was 6 months old. However you did say you are replacing the small tank soon..just make it as soon as possible (tomorrow would be great, get two of them as well). Second...you don't know if his cage mate is a male for female?
If female and both are nearly a year old, it is possible the larger one may be gravid (if it is female). If both are male then there is potential for alot of fighting. If both female then it is better to separate them at least till they are back to being the same size. At least when the new cage arrives, put the larger into it and keep the smaller in the smaller tank to give her time to grow some more.
If one is male and the other female, they should be separated to prevent unwanted pregnancies...though at this point, probably too late for that. Keep them separated at all times, as the female is too young to breed (whether she is already mated or not) and this young age could lead to health problems.
Deffinitely get them sexed or check youself (lay them flat on your hand or table, lift tail to about 90 degrees (be gentle, too sharp of an angle can break the tail) and look near the vent, on the tail side. If you see one bulg, it's a female, if two bulges, then it's a male. If you can't tell you can take it to a knowledgeable vet and he can check for you, either using the method I mentioned above, or other means.