First of all, I would immediately remove the sand/all loose substrates, there are many reasons that they should be on a solid substrate only, but right now with any possible infections/open shedding issues, the last thing you want is for sand to cause an infection to any open areas. All loose substrates breed and harbor all types of bacteria, fungi, parasites, etc. from the minute you dump them in the tank, and dragons are prone to acquiring skin/scale infections, upper respiratory infections, eye infections, etc., so please, dump out all the sand ASAP and then completely disinfect the entire tank and the decor inside, and then just put down paper towels or newspapers in the interim, as a temporary, clean, solid substrate that can be replaced as they get soiled. You can worry about choosing a permanent solid substrate later, like nice textured, slate tiles. But for now you just want to get that sand out of there.
Obviously you already know that you need to get 2 of everything and get them separate immediately, as the domination is already starting between your two dragons, and as AHBD already wisely mentioned, what always seems to happen right from the start is you end up with one Dragon who thrives, they grow normally and are healthy, and then the other dragon is always stunted in growth and development, usually half the size of the other dragon by only 5 or 6 months old, and is sickly, usually always developing nutritional deficiencies/diseases like MBD. So even if you have to buy a 60 or so liter plastic tub from Walmart, put paper towels down in it with a basking platform, and use a clamp lamp to house a Basking Bulb, like you're setting up a temporary rearing tub, that's what you need to do for the health of your dragons. This is the time when they are doing the most growing and developing, and that's why one always ends up not thriving...
While the tail and the spot on his head look to be spots of retained shed (the tail may be a bite from the other dragon, in one photo is looks like it has an open area, but I can't really confirm that, it may just be a kink, but kinks are a sign of calcium deficiency sometimes), I am more worried about the obviously swollen front leg, especially if he's favoring it at all. I don't think that this swelling is due to the shed, it's quite swollen, and if it is in fact painful for him, then you have to be concerned about the possibility of Gout, as it's quite common in young Dragons.
I'm hoping that the moderator, Tracie (Drache613), sees this post and gives her opinion on his front leg swelling, as she's extremely knowledgeable about Gout in Dragons, and I'd really like to get her opinion, because my first thought when I saw his leg was "Damn, that looks like Gout". If so, it's very treatable, but it's important to start treatment ASAP before it gets worse. The problem with such a young baby is that he's far too small to take blood from to test his Uric Acid level, though an experienced Reptile Vet may be able to do a fine-needle aspiration from his leg and then check the fluid for Uric Acid crystals to confirm the Gout.