First of all, remove all "Trigger once" conditions from all events. You are using them wrong and this way they will only introduce bugs.
Do you need to shoot each banana multiple times to destroy? Then "hit" or "health" instance variable needs to be defined on the banana sprite.
Let's say each banana needs to be hit 3 times:
For each banana : Banana add 1 to hit
Banana hit=3 : Banana Play Animation "boom"