Related Questions:
Create a copy of a Menu Item
Copy a Menu or Menu Item
Duplicate a Menu
Answer:
While it is possible to Clone individual Menu Items, whole Menus cannot currently be cloned.
To Clone a Menu Item:
Click Settings
Click Organization
Click Menus
Choose the relevant Menu
Locate the relevant Menu Item
Select the action button (down arrow on the right)
Select Clone
Update the Cloned Item as needed (eg change price, moving it to another Menu)