Duplicate Tab Shortcut by Stefan Sundin

There are several shortcuts available:

• There is a shortcut to open the new tab in a new window.
• There is a shortcut to pop the current tab (or multiple highlighted tabs) out to a new window.
• There is a shortcut to open a blank new tab to the immediate right of the current tab (i.e. instead of all the way to the right).

Tip: Even without this extension, it is possible to middle click the refresh button to duplicate the current tab.

Source code: https://github.com/stefansundin/duplicate-tab

Chrome version: https://chrome.google.com/webstore/detail/duplicate-tab-shortcut/klehggjefofgiajjfpoebdidnpjmljhb