Duplication Bringing Lookup Linked Records to New Record

Hi All

I have a form that is essentially a schedule of courses and dates (which displays these courses on a calendar).

I then have a booking form that has a lookup field that is populated with the record ID of the selected course date.

This enables me to see all the bookings for that particular course date in the course report.

I've noticed that if I duplicate a course, that the bookings on the original course record go to the newly created record (the one made when I hit duplicate). I would think that they should stay linked to the original.

See three screenshots attached.

Shot 1: Shows the original "Schedule Coures" record ID and the linked booking form record.

Shot 2: Shows the new "Schedule Courses" record ID after duplicate and you can see the linked booking form record.

Shot 3: Shows the original "Schedule Courses" record ID after the duplicate that now has no original course booking linked to it.

Any ideas on what might be causing this?