Without the urls, I'm guessing that they have the equivalent of target="_top", or are instant redirects, either of which prevent you from going Back. But it is nice that Firefox is keeping them, normally they would not be the same page.

I have a demonstration of this you can test out for yourself in

http://dmcritchie.mvps.org/firefox/tab_capacity/001_with_underscore.htm

look for target="_top" on the webpage.

Holding the back button to see the back/forward context menu is from Mac usage, you can right-click (Macs used to have one button)

Yeah, it's keeping all the history -- better than deleting it, I suppose -- but I'd rather not have to hit that button numerous times.

Here's an example -- I just tried this moments ago.

• I just opened a new tab.
• Typed imdb.com in the address bar.
• Clicked on a NewsDesk story: Jon Hamm Locks In 'Mad Men' for 3 Years

URL: http://www.imdb.com/news/ni11982605/

• Then clicked on Jon Hamm's name.

URL: http://www.imdb.com/name/nm0358316/

(And come to think of it, IMDb seems to be where I notice this happening the most frequently.)

So the back button just reloads the Jon Hamm profile page again, and ditto when I finally page back to the news story page (takes me two clicks of the back button to go to the page before it).

Odd thing, when I repeated this process -- without opening a new tab -- now I have FOUR of the news story pages in the drop down from the Back/Forward buttons, but TWO of the Jon Hamm profile pages.

Ah, here's an interesting thing -- every time I go to a new page (Hamm's bio, for instance), then go back, there is suddenly one more instance of the previous page.

I've seen literally DOZENS of instances of one page loaded up in this Back/Forward drop-down history. Not the ideal situation, obviously. ;-)

See screen capture below, if that helps.

Thanks again!

Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the extensions is causing the problem (switch to the DEFAULT theme: Firefox (Tools) > Add-ons > Appearance/Themes).

• Don't make any changes on the Safe mode start window.
• https://support.mozilla.com/kb/Safe+Mode

• https://support.mozilla.com/kb/Troubleshooting+extensions+and+themes

Thanks, cor-el -- I used the troubleshooting method and was able to pin it down to one particular add-on. And frankly, I'm surprised.

It's one of the add-ons which I use most frequently: NoScript v2.1.1.1

I even tried reverting all settings in NoScript to their default and restarting, but the problem persisted. Strange that nobody else has noticed this. And too bad, because it'll be hard to replace what that plugin does (until they fix the bug).

I'll let the author know what I experienced.

Appreciate all your help, both of you!

You're welcome

It is possible that redirects cause such multiple entries.

Try the NoScript forum.

• http://forums.informaction.com/viewforum.php?f=3