Cambo
What you proposed isn't really possible in the way you've worded the question. You can't have two engines running at WOT and developing completely different HP when peaked out at the same revs on the same prop. With the same prop at the same revs they must be developing the same HP.

It's possible though to have an engine that could potentially develop 2HP only drive that prop at the same revs either by throttling back (in which case it's no longer at WOT) or by severely overpropping it way down in it's torque curve so it wasn't able to turn that prop any faster. It would then be making the same HP as the other engine and the prop would have exactly the same thrust.