try "pick top instance" as a condition with the collision.
What's the point of the game?
You can fix it also by disabling collisions for all overlapping sprites for like 0.2 seconds when a bullet collides with one of them.
You can also put the condition inside a groupe and disable the group for 0.2 seconds on collision.
Also i advise puttin those overlapping sprites in a family instead of using OR statements and try with trigger once.
The best wat is to post your commented capx tho