However in the duel arena your level is shown as it is normally. But as you probably won't be using summoning when staking this shouldn't matter.
I used to duel alot and being the same combat level as someone is important in order to do 1:1 stake. I think I will not train my summoning atall in order to keep my cb lvl down. Since I won't be using it to stake I won't be needing summoning much anyway!