When trying to restore to a course with an existing ID number, and selecting overwrite settings, the course idnumber is wiped out upon restore.

These courses are linked with an external database. When restoring from another course backup the IDnumber gets wiped out which also causes the teacher/students to become dis-enrolled from the course. The way this used to work (1.9) is that the course idnumber would not get overwritten. I hope this makes sense. We are trying to restore the content from course A into course B. Course B already has an idnumber that is attached to a database enrollment. When you restore course A into B then Course B's idnumber is wiped out.