2 return pumps or 1 on dual overflow

[tank41]

Hello guys. Just need some feedback. Right now I have one 850 gph return pump and two 450 gph return pumps in my possession. I am upgrading from a 75 to a 135 that has two overflows unlike the 75 which has one. So in your opinion would I be better off splitting the 850 or running the two 450's. I know I will eventually need a larger pump but need to go this rout for now. I am thinking I would get a more equal water exchange using two. Any thoughts.
Thanks