Would it cause twice as much evaporation with two sprayer bars? The water coming in is pretty loud, too. I can't hear the filter, but I do have to turn the tv up...
Ditch the spray bar on one or both if you'd like. Does the sunsun come with a nozzle adapter like most other filters? If not you could just get some PVC tubing and a elbow for a few cents from any hardware store and output the return nozzle below the water line. You'll get better flow that way and it's much quieter.
I'll have to check...Not using one of the spray bars was my first thought, but I wasn't sure I could do that. Wouldn't I still have some stagnant spots, though?
Spray bars are good for surface agitation and adding oxygen to the water. They're terrible for flow because they disperse said flow over a large area. It's ok if you have a few spots in the tank that don't have a lot of water movement. It's not a reef tank where you need the current to carry nutrients and food to the coral. The turtle will move water around as well when it swims / moves.