Rated 3 out of 5 stars
I've had to disable it. Every time I start to add tags to a bookmark, the addon asks me if I want to add it as a duplicate entry and automatically closes the bookmark menu; so I have to open the Bookmark menu again and again and again.
On the other hand, when I want to delete duplicate bokmarks, I have to delete them one by one. It takes too much time for my tastes.