HT's favorite description of collisions is that every player is towing a drone through the air. It's behind them on (hypothetically) a 50-foot cable. Now you can't see any other player, you can just see their drone. If you hit that drone, you take damage. If you fly through where the player is, their drone is not in the same space, and you don't hit. If they fly through your drone, they take damage. Now the fact that you're both trailing drones means that for BOTH of you to hit each others' drone, you have to be either directly head-on (not uncommon in AH) or less likely you have to be in some kind of tail chase, something where the paths of the drones are the same and one is closing on the other.
Off-angle double collisions are highly unlikely, because either one of you could hit the drone, but it's not likely you both will (you can't both be behind each other at the same time, see what I mean?)