I think PPE does but not 100% sure.
That's not exactly correct. Each pump will continue to make the full pressure, however the flow demand will decrease by half. Pressure doesn't double, flow does. That's how you get more fuel and still remain within the normal pressure ranges.It depends on how much power you want. In a dual cp3 set up each pump is only used to supply half the fuel. If you rail pressure is at 20k each pump is only making 10k. A stock pump on a stock truck is making 20-25k by itself. The nice thing about using 2 stock pumps is reliability. If you have a pump that can easily make 20k psi and you are only having to run it at 10k in theory the pump should have an easier life. This of course is just my opinion.