If you squint hard at your home page setting, you'll notice it has a vertical bar, and on the right side the Options page address about:preferences. Firefox will load the addresses on both sides of the vertical bar, so you just need to delete the bar and everything to the right of it.

As for how it got that way, ???

Thanks! Pretty sure I know how it got that way. When setting up the browser's homepage, you can see how the homepage selection button was labeled "use current pages" - as in gmail and the preferences tab. thanks again

Use Current Pages always sets all currently open tabs as multiple home pages. You can drag a specific tab on the toolbar Home button to set only this tab as the home page.

yellowbarber said

Thanks! Pretty sure I know how it got that way. When setting up the browser's homepage, you can see how the homepage selection button was labeled "use current pages" - as in gmail and the preferences tab.

Seems like something that should be changed. The odds are, very few people would want that page included with their home pages...