Are you using sync?

If you have sync, and there is a problem anywhere, Shut Down Sync Immediately On All Devices to prevent the problem from spreading. Once the problem is fixed, perform the same repair on all computers/profiles before using sync again.

[v57+] Places Maintenance is built into Firefox.

Type about:support<enter> in the address bar.

You will find Places Database near the bottom. Press the Verify Integrity button.

These copies, are they just showing up anywhere? The same folder as the original entry?

Within some of the folders, not all, last bookmark has been copied several 10+ times. Within the main bookmark tab, about 5 links were copied maybe 100x each. No joke. I got tired of deleting them individually so I'm putting them all into a folder so I can delete them all at the same time. Some of my folders were also copied a few times. I opened the bookmark sidebar and I could see them scrolling down copying over and over again. I have disconnected the sync, but not before it was too late. I tried refreshing firefox and that seemed to stop the multiple copies multiplying more.

Keep an eye on things. If the problem is gone,

That was very good work. Well done. Please flag your last post as Solved Problem so others will know.

You can consider to restore an older backups in the bookmarkbackups folder that isn't corrupted.

• Bookmarks -> Show All Bookmarks -> Import & Backup -> Restore

The name of an automatically created JSON bookmarks backup in the bookmarkbackups folder includes a total item count (folders and separators included) and an hash value to prevent saving the same backup more than once. You also see this count in the Restore menu drop-down list.

• bookmarks-YYYY-MM-DD_<item count>_<hash>.jsonlz4.

If "Verify Integrity" on the "Help -> Troubleshooting Information" (about:support) page cannot repair places.sqlite then remove all places.sqlite files in the Firefox profile folder. 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
• http://kb.mozillazine.org/Unable_to_process_the_backup_file_-_Firefox

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 Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• http://kb.mozillazine.org/Profile_folder_-_Firefox

Thank you! I have searched everywhere for this kind of thing. I think it is fixed now! ~knocks on wood~