Using version 1.1.1 on Windows, not sure if the problem still exists with 1.2.1:
I'm playing as user name "Abc". After many days, I logged in hastily as "abc". I was greeted as a new employee. OK, I thought, the game differentiates between small/capital letters. So I closed the game, opened it again and logged in as "Abc". But again I was greeted as a new employee, with the same employee number as with "abc". If I did not have had a backup of the data from the day before, I would have had to restart now (many hours played).
The reason seems to be that the game internally differentiates between "Abc" and "abc", but Windows does not (when considering filenames). So when the game tries to create a save directory for the new user "abc", it will be the same directory as for "Abc", overwriting the progress of "Abc".
I understand that this diffferent in unixoid architctures. Maybe it would be feasable to test if the supposedly new save directory already exists, and warn the user in that case.
Add: If you can confirm that the save game progress will carry over to the latest version, I'll buy the game immediatly.