Some WordPress installs use very elaborate navigation systems powered by core Menus. They’re a fantastic feature that can often make or break a theme. Menus aren’t very portable out of the box, however. If you’re looking to make a change to a Menu you’re pretty much working live without a quick way to revert back to an old version. That’s where Duplicate Menu comes in.
Duplicate Menu will allow you to create a second (or third, or fourth, etc.) copy of an existing Menu to do with what you will. It generates the clone on a programmatic level and recreates all necessary relationships to ensure the structure is retained as well.
Find out more information in my explanatory article on Duplicate Menu