that uro is a little thin,dont worry im not bashing you at all as atleast your trying so here it goes.
what veggies are fed to them?
remeber lettuce does nothing for them,kale,mustard greens ect. is all good.
get them mixed veggies, there cheap and should last about a week if not over used.
tank size?
two uro's need a big tank,i have my one in a 3x3x3 and i know not all people can afford such enclosures but atleast a 55 for them.
if you live close to me i will give you my 55 to keep as im not using it but you have to live in massachusetts or very close to mass in NH.
try diffrent foods,they like insects but cant be feed to many however this may get them to eat more by making them hungry.
do they have a hide box...mine loves it, not quite a burrow but does the job
hope this helps and if you live close to me i will peronally help you with them
kali

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1.3 Leopard Gecko's
1.0 Mali uromastyx
0.0.3 Tokay's(adults unsexed)
1.0 Water Dragon