What IF, you made that if both planes "collided" (got the collide message) whoever it was that you "collided" with, weather you hit them or they hit you. Hell, even if you hit each other at the exact same time, BOTH planes should go down. Period.
That way, plane #1 doesn't fly off with just a scratch and the other tore all to hell. I don't know a ton about planes and flying, but I would guess if a P51 and a 109 ran into each other IRL both would prob suffer tremendous damage and plumett to Earth.
I don't think one of the pilots closes his eyes before impact and says to himself "I didn't see a collide on my FE, so I guess it didn't happen"