Duplicate Tab allows you to clone a tab along with its history. So you can browse forward or backward in the history of the cloned tab, while reading the current page in the original tab. You can duplicate a tab to a new window or to the same window as the original tab. Duplicate Tab also allows you to open a link in a new duplicated tab, so the new tab will contain the history of the original tab. Another feature is the ability to merge windows: When you have several windows open, you can merge all tabs in all windows into one window, thereby closing the other windows.