moving the basking spot closer to a bulb or increasing bulb wattage will do the same thing and either method is good.
Onto the thread topic, I suggest separating the afflicted dragon from his others, so he isn't stressed. Since you had these dragons for 2 months, and they haven't grown at all, this tells me something isn't right. How often are you feeding these dragons on a daily basis and how much insects per dragon are you giving them?
Hatchling dragons come out of egg around 3-4" or even as big as 5" (this is nose to tail tip by the way. I am also assuming your measurements is also nose to tail tip.) Baby dragons should be offered appropriately sized crickets (dusted and gut loaded) 3-4 times a day, as much as they will eat in 5 minutes. Greens can be provided all day to give the dragons something to munch on between meals, if they take notice of it (many dragon's won't even touch greens till they are 3-5 months old, others eat it immediately).
As you have more than one dragon in the same cage, make sure you have several basking spots with the appropriate temperature. A wide slate stone propped up securely with other stones or some other object is best. You don't want all the dragons lying ontop of eachother trying to get idea basking temps. 'Stacking' is a sign of domination and the dragon's underneath the pile are not getting getting appropriate exposure to heat and UVB and will suffer for it. Ideally each dragon should be housed alone, this will make it far easier to measure how much food each dragon eats and keeping track of regular poops and growth.
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PHLdyPayne