Overflow placement - 1 vs 2 returns?

[albert_dao]

Multiple returns is a waste of time. The return flow from your sump will be negligible compared to the output from a few appropriately sized powerheads -- especially once it's been divided in half and run through additional elbow fittings. It would be like blowing through a straw to try to change the direction of air from a 14" fan.

I'd just go with a center overflow and have the return come through the overflow