This bow uses the XT2000 limbs with single cam. Is it possible to add another half cam or replace both with hybrid cams.

You would have to replace both,the top and bottom cams.Strings,cables and even then,the poundage would most likey be affected.The cost would not be worth it.

It would be expensive and not surehow well it would match up.

The cost of the upgrades would surpass the cost of the bow.

Limbs: $150 - $200
Cams: $80 - $100
New string and cables: $80

If you want a hybrid system, then you are much better off selling your current rig and buying a newer/different model.