message: Fix duplicating unit references when duplicating lectures
diff: @@ -85,6 +85,7 @@ export class CourseManageContentComponent implements OnInit, OnDestroy {
  duplicateLecture(lecture: ILecture) {
  delete lecture._id;
  + delete lecture.units;
  this.lectureService.createItem({courseId: this.course._id, lecture: lecture})
  .then(() => {
  