Hi; congrats on your beardies. We reacue and rehome. Please make sure they are housed in different tanks otherwise one suffers without eating or little eating limited light and UVb & stress u can never hoise 2 on the same tank. Stunted growth is a result of a small tank get a 90 gallon or bigger tank & separate them ASAp. The 6mnth old needs proteins 2-3 times per day; crickets & Dubias are best never ever do mealworms. The bigger one proteins 1-2 times a week. Both always are to be given the greens & veggies daily. Make sure u have the zoomed heat lamp for heat and the Reptisun 10.0 T5 for uvb. It’s a long tubular bulb it should cover 70 percent of the tank. Both need to remain on for 10-12 hours in the winter more like 10 & 12-14 hours more like 14 in the summer. Never use coiled or colored bulbs ever and at nite pure dark and quiet. Also the bigger Beardie needs a temp of 95-97 and the 6mnth old a teeny bit higher like 97-98 until he reaches 9mnths then u can do 95-97. During the day turn on the tv they love to watch soft mellow shows; no violence. Keep the tanks super duper clean they like poop removed immediately & use paper towels or white terry cloths as substrate; never use sand they ingest it.So I got 2 breaded dragons at the se time 2 different places. One is huge the other one doesn't grow hes eats hes active hes lovable but is only 7inchs around 6 months old. The other one is huge.. I have proper Temps and lights. Could it be the bread? These guys might be a month apart.