Single vs Twin motor for an electric RC airplane
You should keep in mind that adding an engine adds wiring, extra propeller (a larger single prop might to be lighter in RC than an equal setup of two), overall complexity etc.
As I understand it, electric motors have a &quot;sweet spot&quot;, or rather an area of (iirc) certain load and rpm. You should desing your configuration so, that the motor(s) would operate in this rpm/load range in cruise. This sweet spot is (again, iirc) much higher than half load. So it is likely you are better of with a single engine than two that are only utilizing about half their rated pwr.
This sweet spot is very motor specific, so you need to dig deep into spec sheets.