Hi,
I didn't assume it's a loadlevel issue herem and I agree: making repro projects requires skills and patience.
I am having this very issue with the new 2d physics collision, a nightmare! I get repeated TRIGGER ENTER events ( outside playmaker, in an actual regular scripts provided by unity learning team...) and the actually unity sample simply accepts that ( which is beyond me...) and simply listen and filters accordingly. That's why I am having some trouble providing the unity 2d sample as a playmaker solution, I need to overcome this first because within Playmaker, everyone would get very confused, and for very good reasons... but I fail to find a workaround since it's coming from Unity itself to begin with...
Back to your case
What could be happening is something outside playmaker, and playmaker simply forward the call twice, because it indeed received it twice... that's likely the case ( can't really say for sure, but 90% sure)
So, you are not alone here
and the quickest solution is to "accept" it and maintain flags. I am not saying it's a good solution...
but it's one that will let you move on.
Can you come back to me next week or aftetr xmas ( I know.. it's far away... but I am swamped...) and keep bumping me so that I have a proper look at this and point at the source of the problem for sure.
Bye,
Jean