One thing that will work with course copying is to link to the Moodle resource rather than the file directly:
https://yoursiteurl/mod/resource/view.php?id=506322
If you have the file resource configured to "Open" it should display in an iframe the same as it would if you clicked on it from the course page and when you copy the course and the new resource is created, the link should point to the newly created link rather than the old one
https://yoursiteurl/mod/resource/view.php?id=506322
If you have the file resource configured to "Open" it should display in an iframe the same as it would if you clicked on it from the course page and when you copy the course and the new resource is created, the link should point to the newly created link rather than the old one