Hello! I found a similar question asked with a solution provided if you'd like to take a look and see if it helps you any. If not, let me know and I can do some extra research. :)

https://support.mozilla.org/en-US/que.../1020435

I came across this too. Maybe this could help?

https://dottech.org/162426/how-to-delete-duplicate-browser-book...

I came across this as well. Maybe this could also help. :)

https://dottech.org/162426/how-to-delete-duplicate-browser-book...

Hello! Maybe this could help? I found similar question asked with a solution provided. :)

https://support.mozilla.org/en-US/que.../1100812

I also came across this. Maybe this could help as well?

https://dottech.org/162426/how-to-delete-duplicate-browser-book...

Ah, sorry if you received multiple replies from me. My screen was acting up and I couldn't tell if they sent or not. Can you see my replies?

But please do let me know if there's anything more I can do to help.