If you want to duplicate your open presentation, you can save it using a different name or location.
Choose File > Duplicate.
An untitled copy of the presentation is created. Both copies remain open on your desktop for you to view or edit.
Close the window of the untitled copy, type the presentation's name, and then choose a location from the pop-up menu.
Click Save.
Choose File > Save As and specify a new name or location.
When the presentation is copied in this way, the original presentation is closed; the presentation that remains open on your desktop is the new copy you created. To work with the original version, choose File > Open Recent and choose the previous version from the submenu.
You can also automate creating a backup of the presentation every time you save, retaining the name and location of the original, but with the words “Backup of” preceding the filename. See Automatically Saving a Backup Version of a Presentation.