This issue has crept up several times lately. The concept of housing several chams together is interesting , but in the best case , it still will create stress.I have seen a keeper, house 2 seperate 1.3 colonies of Panthers in large 100 gallon reptariums, with a ton of foiliage and in each case the chams seemed really well adapted. But, within about 3 - 4 months time , a pecking order began to develop.. competition for territory , food and basking time all ensued. Eventually chams became ill and deaths followed.
The effect of stress is usually apparent after it is too late.