Copying a menu can be a useful tool for many scenarios. For example, if you decide you are going to have a weekend beer menu and the menu will only change slightly, you can create a copy of the main menu to use as a base.
To start, check the box to the left of the name of the menu you'd like to copy, and when the controls appear on the right, click Duplicate:
You will have the option to rename the menu (the default name will be "Copy Of menu name"), as well as choose whether the menu should be created in Published or Unpublished status. When you have made your choices, click Next:
Now you will have the opportunity to review your selections. If everything looks good, click Duplicate Menus:
You will now see the new menu on your menu management page where you can work with it as normal.