That would defeat the purpose of arena...
The way things are supposed to go is that double healer comps do significantly less damage than a double or even a single dps team.
The problem is healing being very strong at the moment (about to be nerfed in 5.3), and healer DPS being very strong.
Restricting arena comps would be defeating the purpose, and throwing the baby out with the bath water so to speak.
ALSO, why restrict 2 of the same class? Diminishing Returns on cc abilities makes 2 of the same class weak.
I'm sure you're thinking of prot warriors when you make that statement. If your team cannot deal with splitting up damage from 2 classes with no consistent burst, I suggest getting a new partner or using different classes....