Duplicate Key Error when Adding Student Enrolments

[applebyter]

Bug Description
When I try to add student enrolments to the CSSE6400 course I get the error message:
duplicate key value violates unique constraint
"UQ_efc6e6ce1d0a41624e195edf963"

To Reproduce
Steps to reproduce the behaviour:

1. Go to the Student Enrolment page.
2. Select the course CSSE6400.
3. Upload a valid file containing student enrolments.
4. The message "This file seems valid" and the enrolment preview are displayed.
5. Click the Apply button.
6. The indicated error message appears at the bottom of the browser window.

Expected Behaviour
After step 5 above, the student enrolments should be added to the course.

Screenshots

Desktop

• OS: Windows 10
• Browser: Chrome
• Version: 111.0.5563.65

Additional Context
The same process of adding student enrolments works for other courses. I added student enrolments to COMP2048 earlier on the same day, from the same computer, and using the same browser.