Ah, I see what you mean now. Your problem here is that when the "Collision" objects collide with each other, the "Collision" objects are the ones being picked.
You want to pick the "Main" object and apply events only to that.
In order to solve your problem you'll need to track which "Collision" object is connected to which "Main" object.
One way would be an instance variable to store the collision UID: