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This continues to happen for me and while I'm using EverHelper to remove the duplicates, the problem still returns. I have only 10 bookmarks in my Bookmarks Bar, yet I've had to delete 600+ duplicates in the last week alone. This is untenable.

Any feedback on this? I'm having the same problem. I tried overwriting the server data to assure it's only the bookmarks that should be there, but a few hours later, VIOLA, I've got double (and later triple, and so on) the bookmarks I had before and they are simply duplicates of my actual bookmarks.