When you imported your bookmarks you have most likely imported bookmarks from way back when you installed the browser. Whenever you install a browser it gives you an option to import bookmarks from other browsers and it adds them to your bookmarks there and puts them in separate folders where they usually get forgotten about resulting in several duplicates that are in different directories. After a few re-installs of a browser or even if you have imported bookmarks from more than one other browser the number of duplicates that are in folders can be very high. Eversync for bookmarks works great for me but I suggest if you want to organize bookmarks or better understand the process this is a good link to check out... How To Dedupe Your Chrome Bookmarks