Ok, i saw this and it is somewhat similar but i wanted to check if it is resolved already or whether its the same issue.
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When the mesh detects there is a overlap with a projectile it fires an overlap event, but it is fired multiple times.
As you can see from the video it is firing multiple times the first time I press the mouse, but it is executed only once when i press the LMB multiple times.
the blueprint for the event is just to attatch a emitter. If you need it I will upload screenshot when i get back home.