[SIS] During import, warn for multiple enrollments of same person/course or section/role

[JoshuaAlbertson]

Problem statement:

If you have duplicate enrollments of same person/course/role but different statuses in your SIS import file they will be processed without warning or error. Because Canvas breaks SIS import files into chunks for processing it can't be known which of the statuses from the duplicate enrollments will be used.

Proposed solution:

When SIS Import enrollment file is processed issue warning or error that there is a duplicate enrollment

User role(s):

admin