not useful Rated 1 out of 5 stars

Warns me after the duplicate webpage has loaded 100% ...

Works Rated 4 out of 5 stars

It does what it says, but I cannot find any configuration options.
I would like the warning to be within Firefox and not using the OSX notification center.
Also I would like it to just auto switch, and not give the option to close.

Works great! Rated 5 out of 5 stars

Works like it says. Up till now I ve tested all available addons for duplicate tabs handling and liked none. Other similar addons wont let you open a duplicate even if you want to and others will kill the old tab (instead of the new one) loosing its tab history. After using it for months these are my conclusions>
Pros (Compared to all other similar addons):
1. It warns you and lets you chose whether you want to leave the duplicate load or kill it.
2. It kills the duplicate tab not the original (most times this is the right choise).
3. After killing the duplicate it directs you to the original tab so you dont have to search for it manually.
4. Even if you miss the warning or chose to not kill the duplicate the page and the tabtitle are changed to remind you that it is a duplicate.

Cons:
Warning on/off and warning timer settings would be nice.

Even without setting it still works as it should thats why I give it a perfect rating. This is by far the best addon for duplicate tabs handling.and using it along with "All Tabs Helper" I eliminated my multiple duplicates problem.