What telemarkbrew just said is the ideal way of performing a single batch sparge. Equal runnings size maximizes efficiency given the constraint of two runnings. Three runnings of 2g each would be a little more efficient (2-3%) but requires an extra stir and vorlauf. You decide.
I decided a long time ago that for the extra effort it just wasn't worth the time or effort. I average 82-84% with a single sparge and that's good enough for me!