Manually added calendar events are always imported, and there is no check box to de-select events. Users must manually delete any extraneous calendar entries after importing.

To reproduce:

In course A -
Make sure the course contains a resource or activity
Add a calendar event

In course B -
Select Import
Choose course A
Select any resource or activity to import

The expected result is that only the checked resource or activity should be imported.
The actual result is that the calendar event from course A also gets imported to course B.