Hi,
I was having the same issue, but with the blockers instead of the coins. I used print string to confirm that this is exactly what was happening. As soon as the game started the blockers generated the overlap event. I dont know if this is a bug or we are making a mistake somewhere but i do have a workaround.
I saw from the print string methods that it was in fact the RunCharacter that was triggering it but it was nowhere near the blockers.
I also saw that this happened only once per blockers the instant game started.
So i used a branch to make sure that nothing happens in the overlap event when the game started.
So when the world delta seconds is 0.0, meaning game just started, the overlap events still fire but they wont do anything.
Hope this help you.
If someone knows what exactly is happening, let us know please, Thank you.