Where do you see these duplicates ? Did you create them yourself or do you possibly see them in a 'Recent' type of list ?

If you use Sync then best is to disconnect Sync temporarily during troubleshooting.

This can be caused by a problem with the places.sqlite and favicons.sqlite databases in the Firefox profile folder.

• use "Verify Integrity" button on the "Help -> Troubleshooting Information" (about:support) page

If errors are reported with "Verify Integrity", close and restart Firefox or reboot and retry.

If "Verify Integrity" cannot repair places.sqlite, rename/remove all places.sqlite and favicons.sqlite files in the Firefox profile folder with Firefox closed. Firefox will rebuild places.sqlite and restore the bookmarks from a recent JSON backup in the bookmarkbackups folder.

• keep a backup copy of places.sqlite in case a new places.sqlite database has to be created

You lose the history when a new places.sqlite is created.

See also:

• https://support.mozilla.org/en-US/kb/Bookmarks+not+saved#w_fix-the-bookmarks-file
• https://support.mozilla.org/en-US/kb/fix-bookmarks-and-history-will-not-be-functional

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

• Help -> Troubleshooting Information -> Profile Folder/Directory:
  Windows: Open Folder; Linux: Open Directory; Mac: Show in Finder
• https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data

cor_el, let me start by apologizing for troubling you twice over this issue; my memory isn't what it used to be. As for the problem, I deleted Places.sqlite and favicons.squlite. Upon restarting Firefox, I found I had the same problem, Your second link suggested I make sure that places.sqlite wasn't marked as "read only;" unfortunately, that seems to be the case. I could find no provision for changing that status, so should I consider a new profile?

You can always try to create a new profile as a quick test to see if your current profile is causing the problem.

See "Creating a profile":

• https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles

If the new profile works then you can transfer files from a previously used profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over problems.

• https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile

cor-el, thanks. The new profile seems to do the trick. I'll get right on copying files over.

co-rel, I found that my handlers.json file caused the problem, so I deleted it. Things look better now, especially since the places.sqlite file is no longer read only. I hope this banishes the problem. Should I delete the old profiles?