Undo a closed Tab(s) or create a duplicate of your current Tab with Undo|Duplicate Tab addon. Some features: 1. Allows you to restore a closed tab(s). 2. You can easily make a duplicate of the current tab. 3. Toolbar popup UI has two easily accessible buttons (undo & duplicate). Note 1: this addon only works with Firefox version 52 and upwards Note 2: in order to report bugs, please fill the bug report form in the addon's homepage.