Moving back to Assigned as I am unable to verify the correct functionality using today's update to gdm-3.28.3-28.el8.x86_64
I believe I have all the correct settings. I have verified my steps on RHEL7 where it works correctly.
[xdmcp]
Enable = true
AllowMultipleSessionsPerUser = true
Second client will still return me back to user selection screen upon trying to log in.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://access.redhat.com/errata/RHSA-2020:1766