What pages are loaded in those 2 tabs?
Or are they empty or "new tabs"?

What pages are loaded in those 2 tabs? --> it is only empty tabs, just like you open a new tab. Or are they empty or "new tabs"? --> New tabs and empty. Eg, one tab with Home Page, and two more empty tabs appeared when first starting Firefox.

Hello,

Maybe Another user had a second tab opening and it was caused by one of his extensions.

You can check for nonessential or unrecognized extensions on the Add-ons page. Either:

Ctrl+Shift+a

Tools menu > Add-ons

In the left column, click Extensions. Then, if in doubt, disable.

Usually a link will appear above at least one disabled extension to restart Firefox. You can complete your work on the Add-ons page and click one of the links as the last step.

Does that get rid of the extra tab?

Thanks Shashank, but I tried that. No, it does not work. This is a new computer, which I bought last Saturday. I only sync the bookmarks with my old computer, which does not have this problem. Only happen in this New computer, and I have no idea how it happened.

I am attaching two pictures to show the real problem.

Hi all, I just resolved my problem myself. I accidentally reset the Firefox to default setup, and I need to sync with old computer again on the bookmarks. I noticed that in my old computer, I have two extra New tabs, I quickly stop sync it, deleted the two New tabs, and started the sync again. After that, I restarted my Firefox in my new computer, it only shows one tab. So, it is the problem in the sync process, that they will remember how many tabs opened in my old computer.

Thank you for all help from the Community. Appreciate your effort.