You can only do this by converting to an app page. Then you could save a copy of that app page as a personal page (or multiple pages). If you then wanted to delete the app page you would have duplicate personal pages.
@Erwanlenavenec You could go back to the original page and choose to create another personal page. This will then give you two "My Pages" for the same original page. You could then make the same edits to both "My Pages" to ensure they are the same.