The thing with the plugins that allow you to duplicate subsites in a WordPress Multisite Network is that they all are pretty complicated, usually, there is a separate WordPress admin interface which is in a different style than a WordPress admin dashboard itself.

The idea behind this plugin is to provide the possibility to clone a sub-site using just quick action links, which is a standard WordPress UI. 

It seems simple, however, the plugin still comes with a bunch of features.

Features

• Exclude any post types and post statuses when duplicating a subsite.
• Decide, whether to add a user to a cloned subsite as an administrator or not.
• Choose specific database tables that need to be duplicated along with a subsite.
• You can turn off duplicating media files if you don’t need them to be copied.