This is an easy one to answer for you completely: YOU NEED TO SEPARATE THEM IMMEDIATELY, THEY BOTH MUST HAVE THEIR OWN ENCLOSURE/TANK, LIGHTS, ETC. AND YOU MUST EITHER STACK THEIR INDIVIDUAL TANKS ON TOP OF EACH OTHER SO THEY CANNOT SEE EACH OTHER ANY MORE, OR BETTER YET, YOU MUST KEEP THEIR TANKS IN COMPLETELY SEPARATE ROOMS FROM NOW ON...
This is probably the most common problem that we see, as well as the most common result of the problem. Bearded Dragons are naturally, in their indigenous environment of the Australian Desert, totally and completely SOLITARY ANIMALS...The only time you will ever see 2 wild dragons together is when a male and female come together to mate, then they immediately separate, that's it. The female lays her eggs and leaves, the babies hatch and separate. They live alone, all the time, and when we as their captive owners force them to live with another dragon (AND NOT EVEN IN THE VAST DESERT, BUT RATHER IN A TINY TANK) we cause them enormous amounts of intense stress, every second of every day.
The typical outcome of housing 2 or more dragons together is that at least one of the dragons ends up extremely stunted in size, lethargic, emaciated, dehydrated, and eventually they usually die of a condition such as calcium deficiency, starvation, dehydration, etc. So often times you will get one dragon (the dominant dragon) who thrives, and one dragon (the submissive dragon) who dies...It's also not uncommon at all for both (or all) dragons to end up this way.
The problem is convincing people that this is the issue, because from our outward vision, if the 2 dragons aren't being "aggressive" with each other or hurting each other, then there isn't a problem (which WILL HAPPEN some day, it may be today, tomorrow, next year, or 4 years from now, but it WILL HAPPEN, suddenly and traumatically, one bite to the skull and that's it). The truth is that your dragons are being terribly stressed every second of every day, and you as a person cannot see it. They don't talk, so we can't see it. But there is a power-struggle over the best Basking Spots with the strongest UVB and UVA light, the best live insects, the best greens and veggies, the best spots regarding temperatures, etc. Everything, everything is a power struggle. This is resulting in such stress that their appetites are decreasing, they end up not basking properly or getting anywhere near enough proper UVB/UVA/UVC light, they are literally afraid to live properly.
Unfortunately this will not ever stop unless you separate them immediately and get them each their own tank/enclosure, their own UVB and bright-white colored Basking Bulbs, Basking Spot/Platform, carpeting, everything. They each need their own, entire tank set-up ASAP. If you don't separate them now, they will not grow, they will be stunted and emaciated, and this is going to end either in a horrible, violent act of aggression, which typically kills one or both of them in a horrible way, or one or both of them eventually develop severe MBD and the paralysis that comes along with it, and they will eventually die from this, but they will be much longer, drawn-out, painful deaths.
If you do your research on here and other forums you should find the same answer, I've probably answered this question with exactly the same situation and problems presented in the OP's first post around 200 times, no joke. Because pet shops and breeders both refuse to tell people that they cannot keep 2 or more bearded dragons in the same tank this happens every day. It's a shame that they are only interested in selling 2 or more dragons instead of just one that would be healthy, they know that if they tell the customer that they cannot keep 2 or more dragons together that most customers will then only buy one dragon because they don't want to pay for 2 complete set-ups, or they can't afford to. It's terrible. And we become the bearers of bad news...
If one dragon is worse-off than the other, then that dragon must be left in the current tank, as they can't take the added "Relocation Stress" of moving to a new tank. If you can find a second tank of adequate size (at least a 40 gallon breeder tank) on Craigslist, along with additional light fixtures that's one way to go, but if money is a problem, then we usually suggest going to Walmart, Big Lots, etc. and buying a large, clear plastic tub, at least a 60 Litre one (depending on age/length/size of the dragon you're moving), they are pretty cheap, and then spending the bulk of your money on the best UVB tube and tube fixture you can afford.
Ensuring that both these dragons have a strong, adequate UVB tube and tube fixture is going to be the most important factor here, because they are already stunted in size and suffering from a severe Calcium Deficiency, and without a very strong UVb tube, preferably a T5 strenth 10.0 or higher UVB tube, they will not be able to absorb or process any of the calcium or other nutrition that they eat or ingest in supplements, and they will not start to grow again, nor will any of the damage be reversed. You can buy a 22" Reptisun 10.0 T5HO UVB tube on Amazon.com for around $24, and the cheapest 24" T5-rated tube fixture with a metal reflector inside it that I've seen is also on Amazon.com, it's costs around $28. So you can buy one of the best UVb tubes available for a bearded dragon, along with a fixture for it on Amazon.com for around $50 total. Also, if you go the plastic tub route as a temporary enclosure, you can simply buy a cheap, aluminum reflector Clamp Lamp at any Walmart, in the aisle that has the extension cords and wiring/electrical supplies. They have 3 different sizes of aluminum Clamp Lamps, a 4", a 6" or 8", and a 10", and the middle size is perfect and costs about $6. You can then just attach the Clamp Lamp to the top edge of the plastic tube, and you can put the long tube UVB and the tube fixture across the top of the plastic tub, right alongside the clamp lamp that holds the bright-white colored Basking Bulb, which you can simply just buy a 100 watt Halogen Indoor Flood Bulb for, at any Tractor Supply, Walmart, Lowes, Home Depot, etc. You need to set the plastic tub up with a Hot Side and a Cool Side, just like you would a regular tank, and it will work very well.