Endnotes creates endlessly copies of the same pdf

Hi,

Did anyone observe this problem?

Endnote creates endlessly copies of the same pdf of one reference, so that I get (currently) about 300+ identical pdfs within one reference. They all get a new single folder, and the indexing number is increased by one every time Endnote creates a new doublette.

The database is shared/synced with two colleagues. I fear, that everytime Endnote syncs with the web database it creates a new doublette. Is this possible?

Wolf