You can duplicate all creations from the "My account > My creations" tab (the "duplicate" option is underneath the creation). You can save it as "Copy of..." or change the name when confirming you want to make a copy.
Creations made in the new editor can also be saved through the editor:
In editor:
• Click on the "menu" (three horizontal lines) in the top left corner.
• Click on “Duplicate creation” and confirm your choice.
• By default, your creation will be named as “Copy of…”, but you can change the name.
• Once you save the duplicate’s name, the duplicated creation stays open in the editor.
• To return to the original creation, click on "My creations" link from the editor. This will take to the "My creations page", where you will find your original and the duplicated creations.
Please note: The duplicate option becomes active once the original creation is saved for the first time. It will remain disabled for guest (not logged in) users.