It is possible to have multiple users that come with the same name (but different username), e.g.
heimueller, Heinz Müller
heimueller2, Heinz Müller
Opencast cannot handle this situation when it comes to user groups: In Organization->Groups->"Edit Group", there would be only one "Heinz Müller" displayed. Even if both users would be displayed, there would be not indication of which "Heinz Müller" is which "Heinz Müller".
I therefore suggest to display not just the user's name but also his/her E-Mail address in the list to correctly handle this situation, i.e. the users are listed like:
Heinz Müller <email@example.com>
Heinz Müller <firstname.lastname@example.org>
Having the E-mail address directly available in the lists also makes it easier to contact users if required (no need to lookup the users table).