Hours gone to waste because of this piece of crap. Instead of closing just duplicates, it closed all tabs that I had 2 or more of open. So for example, I had two copies of a tab. It closed them both. Ctrl-shift-T only goes back so far. I'm going to have to start all the way back at the beginning now. I can't even express my rage at this useless extension. I completely regret I ever got it.