Hello coatli,

You could do this : hold down the CTRL key and then type (lowercase):
L C T V ENTER.

But maybe you'd rather give this add-on a try :

https://addons.mozilla.org/en-US/firefox/addon/duplicate-tab-shortcut/

Any good ?

great, thanks! :)

coatli said

great, thanks! :)

    My pleasure !

I know you asked for a keyboard shortcut, but there are more ways apart from via the right-click context menu.

You can middle-click the combined Stop/Reload button with the mouse scroll wheel to open (duplicate) the current tab in a new tab. This include the Back/Forward history of the current tab. You can hold the Shift key to toggle loading in the background (keep focus on the current tab).

You can use Ctrl+L to set focus to the location/address bar and press Alt+Enter to open the selected URL in a new tab. You may have to use Ctrl+A or ESC in case the URL isn't selected.

thanks!