I agree with the above. Your more pressing issue here is head loss. A larger return equals less shearing (Friction) and therefor a higher GPH on the return.
Having two drains doesn't help that much as they still have to balance the return. So if the system is balanced with two drains equaling the GPH of one return, then if one of the drains plugs, the other remaining drain still won't be able to handle 100% of the overflow.
Also, a wider drain is less likely to plug!
Cheers