Josh, there are options above 1" - and it is Canadian made! I have the 1" versions of these and they are the bomb.Dropping to 1" at the split gives you return Nozzle options. There are no return fitting options other than basic PVC fittings once you go larger than 1" and even at 1" you're pretty limited to VCA Random flow Generators. As mentioned above going from one 1.5" line and splitting to two 1" returns will provide more flow than through the 1.5" and still give you return fitting options.
To set this up you would increase the 1.25 at the pump to 1.5 then purchase a reducing T or Y and install it as close to the return outlets as you can on the 1.5". This will split your return from 1.5 into two 1" lines with one fitting.
Personally I think if you would like to run dual pumps, have two entirely separate return lines. Oh and I'll add, whatever you do, DO NOT have holes drilled for 1.25" bulkheads. They are next to impossible to find lately and you might find yourself with holes in your tank you can't use...
1.5" Omni-Flex Nozzles from OceansMotions... you can adjust these to point anywhere you want. Available only in 1" & 1½".