Currently to duplicate a site, it's a very manual workaround where you have to import one page at a time into a new site. This requires a lot of work to then switch site resources to point to the new site rather than the old one.

Duplicating a site would create an identical copy of a site, including publish history, files, etc. This would allow users to retain older versions of a site, but provide a quick starting point for creating an updated design. Duplicating a site can also be used to create staging versions of a site to safely work on new components and content if needed.