When placed in Start() causes a delay and multiple initial spawns.
Depending on the time it takes to initialize the project, will ultimately determine number of spawns.
Alter the fireDelay for proof of this problem.
This can further be described that anything that you have in your start that has the ability to spawn objects over a given time can in fact spawn many items up until the scene begins its render.
Change fireDelay from .4 on up and restart the program, on each start depending on the fire delay, you will witness the problem.
37293–1391–$collisionexample_173.zip (225 KB)