Just ran into this upgrading from 11.10 to 12.04 Beta 1. I got a pop-up complaining that the installation of update-manager-core had failed because of a problem with exc_tests.py (I'll file a separate bug for that), then later I got a separate pop-up with the "already installed and configured" message. This was in a 32-bit VirtualBox VM.
Just ran into this upgrading from 11.10 to 12.04 Beta 1. I got a pop-up complaining that the installation of update-manager-core had failed because of a problem with exc_tests.py (I'll file a separate bug for that), then later I got a separate pop-up with the "already installed and configured" message. This was in a 32-bit VirtualBox VM.