A lot depends on how the pool is plumbed.

Did they run separate lines for each skimmer or tee them together, separate you have control by valving them at the equipment ,also your return lines should be aimed at the skimmer across the way pushing towards it , is it 1 1/2 in plumbing or 2" alot of variables, a 1 hp should be enough in most cases you have to look at cost of operation vs time ( a small pump running 8-10 hrs /day or a larger running 6/day)