You don't say where you live. How do you plan to control mosquitoes? Even 1 400gph pump should be ok for you. What model number and brand are they?

I'm in Northeast Pennsylvania. It doesn't state what brand or number for the pumps. I haven't received them yet, I ordered them a few days ago. It's the TotalPond starter kit and a Beckett waterfall kit. I was hoping to add 2-3 feeder goldfish or some minnows for mosquitoes but if my pond wasn't big enough for that I would use mosquito dunks.

Your pond is plenty big enough for 2 or 3 goldfish. They'll take care of the mosquitoes.

You don't Need both, but you can run the second one anyway. For example, you could create the appearance of a side stream entering the pond. You might enjoy looking at cliffandjoann's posts. There is a specific post about using cheap harbor freight pumps for that purpose. Otherwise they would be for aspiration but the secondary pumps look real nice.