[Bugfix] drop down list of students duplicate display of non-null/null (#3772)
[Bugfix] drop down list of students duplicate display of non-null/null (#3772)

* updated getAutoFillData() to avoid duplicates, add removeStudentWithId()

Signed-off-by: fenn-cs <5381408ef480ba9c0b40bdd3d7a3fc527364a2b4@gmail.com>

* updated getAutoFillData() to remove NULL students from regular section

Signed-off-by: fenn-cs <5381408ef480ba9c0b40bdd3d7a3fc527364a2b4@gmail.com>

* added docstring for removeStudentWithId

Signed-off-by: fenn-cs <5381408ef480ba9c0b40bdd3d7a3fc527364a2b4@gmail.com>

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