Your first running should be the highest. The second running should dilute you down to close to your pre-boil. Boiling will concentrate the wort and should give you your post boil at the predicted post boil volume.
Compare your 1st running gravity to table 1 here:Braukaiser
. This will tell you how well you are converting in your mash. You should be able to achieve percentages in the 90's.