Rated 3 out of 5 stars

le Alice ar Lún. 14, 2014 ·

It does the job of preventing you from opening duplicate tabs, although giving us the option of the addon making the duplicate active or not would be nice. And on top of that the addon conflicts with another of my addons, I believe TabMix Plus, preventing TMP's session manager from working at all and even causing Firefox to close without any errors.