These Reports are only available if you have Logon Monitor installed.
I want to know if a username has been used to log on at more than one workstation simultaneously.
The Simultaneous Logon Detailed Report monitors the simultaneous logon of a small number of users. The Report contains the username, the computer name, the start time and end time of simultaneous logons.
I want to know how many simultaneous logons have occurred during the past week.
The Simultaneous Logon Summary Report monitors the simultaneous logons of all users. The Report contains the username and the number of simultaneous logons. You must specify the top 'n' number of simultaneous logons. By default, the 30 usernames with the most simultaneous logons are reported.