Possible Bug: Error message when student appears twice in export

Summary

Apparently during the last c course exam there was a problem with the ILIAS export where a student appeared in two rows of the export file and and the accomodating table sheet was empty.

Steps to reproduce

Example Project

What is the current bug behavior?

The converter apparently didn't issue a warning when it was used at that time. I'm unsure if this may already be fixed in the latest version.

What is the expected correct behavior?

The converter should output helpful error messages/warnings in case any irregularities (like a student appearing twice) appear.

Relevant logs and/or screenshots

Possible fixes

Check if students appear twice, output a warning if they do.