Announcements emails are send twice to tutors/editors

[fh314]

Describe the bug

As an editor of the EIST courses, I always receive the announcements emails twice.

To Reproduce

1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

Expected behavior

Only send announcement emails once to editors/tutors

Screenshots

No response

What browsers are you seeing the problem on?

Chrome

Additional context

No response

Relevant log output

No response

[krusche]

I think this happens because we have two courses with similar announcements, one for Garching and one for Heilbronn.
Did you double check that you received the exact same email with the same course name?

[fh314]

Yes, I did get two emails for Heilbronn and Garching each

[krusche]

Are you maybe listed twice in the course? For example as tutor and as editor?

[fh314]

Apparently that seems to be the problem. I don't know if fixing this behavior is of any priority so feel free to close

[krusche]

We should definitely fix it and take a set-based union of all students, tutors, editors and instructors of the course before sending the emails to avoid potential duplicates. Should be relatively easy to implement if someone finds the corresponding source code

[ge65cer]

Duplicate of #5246