At present, activity duplication (one-step backup + restore) is quite long-winded.
We can easily cut this down by moving the confirmation message to a moodle-core-dialogue-confirm which then hands the actual work to course/rest.php to be performed in the background.
This would use similar code to the coursedndupload to add the new activity without a page refresh.

Needs some more general throught before implementation. I think it's about time we extended moodle-course-base to add functions to do things like:

• create a new section; and
• create a new course_module instance.