[Bug]: Redundant course allowance

[wenbowang2002]

Describe the bug

Redundant courses are allowed in the same term/ different terms.

How To Reproduce

1. Add two same courses in the same term / different terms.
2. Save.
3. The course will appear on Magellan in the latest term that it appears on Elcano.

Expected behavior

Redundant coursers are prohibited, unless the course needs multiple terms to finish.

What device were you using when you encountered the error?

Windows laptop

What browser were you using when you encountered the error?

Chrome

What operating system were you using?

Windows 10

Additional Information

No response