When the caller types in "michael" and presses #, the system should come back and say "Two matches were found for the name entered. Press 1 for (And now you hear the name that Michael No. 1 recorded when his mailbox was logged into for the very first time), press 2 for (and now you hear the name that Michael No. 2 recorded when his mailbox was logged into for the very first time)"
I would go to the System Administrator's mailbox, select 2 for extensions, 1 for name, 1 for recorded name, and 1 again to listen to what has been recorded for each of these mailboxes. If they have not recorded their names properly, you can do it for them from there, or MAKE them go to their own mailboxes, select 3 for Name or Greeting, 2 for Name, and re-record it right.