Rated 4 out of 5 stars
> f the URL in the address bar is highlighted (shortcut for that is F6), pressing Alt+Enter will duplicate it. There's no need for that part of this add-on, it's built in.
Built in, yes. But you need three key strokes and two hands for it instead of you one click... So this is very useful extension. If only it would also duplicate the tabs history too.