How realistic does this sound? I'd like to use the Heal the Focus's Target's Target style of Macros for most heals (except group/aoe heals like POM and Prayer of Healing)

Priest 1 Focus Priority List: MainTank, OffTank, Self

Priest 2 Focus Priority List: OffTank, Main Tank, Priest 1, Self

I'm asking because I'm considering leveling another priest and dual-boxing for Kara raids. Has anyone tried to do that already?