Simple and neat. Works fine.
Still, you can get the same result without the extarsion by Ctrl+LefyMouseClick on the Reload button...

It has most of the features I'm looking for (on top of duplicating tabs):
- right next to the source tab
- keeps the history

Just one big missing point is a keybinding. I'd be glad to have Ctrl+Shift+D to duplicate the current tab, since it would help a lot not to use the mouse when you don't already have your hand on it.

Edit:
I haven't found a way to answer directly to your reply, so I'll do it here.
I've rephrased the comment so it's clearer.
About the shortcut, I'll try at home tonight (on Linux), but here on OSX it doesn't work, I guess its because Cmd+Shift+D already exists :/

This is an excellent extension! Thank you so much, author!

My one gripe is that right now only supports the Option-Shift-D shortcut for duplicating tabs (on OS X, different on Windows). It would be great if this was customizable. I'm used to having Command+D duplicate tabs, and it's confusing the hell out of me (I keep bookmarkin pages accidentally).

I'll be updating this to a 5* review once that function is added!

Duplicate works properly now but there is a delay before the duplicated tab is made active. Maybe instead of waiting for tabs.duplicate add a listener to tabs.onCreated and assume the next tab created is the duplicated one, make it active, then remove the listener.