I do the same thing every time...drag and drop publicity .pdfs into the import folder, usually one at a time, sometimes 2-3 depending on the project. Most actions get the expected result but a small but significant anomalous number freak out the app and start generating endless duplicates. The only way to stop is to close the app and empty the import folder. Unfortunately if I don't monitor EN at all times as I import, the duplicates can go completely off the chain. Most recently it had over an hour to generate duplicates before I noticed. If I could simply delete the duplicates I wouldn't be here, but at 50 a pop the deletion is still not complete several days later.
I have analyzed the problematic .pdfs and see nothing that would seem to cause the problem. They come from different sources, have different layouts, different content. No apparent "issue" that should cause this.
Data point: I just dragged and dropped the "problem" pdf that caused the most recent issue into import folder again. One copy of the note was generated as would normally be expected. No duplicates. That would seem to indicate the .pdf doc is not the issue. I didn't do anything differently. Of course, there have been at least 2 EN updates since the recent incident. Maybe 3.