Core issue
This issue is occurs due to the presence of Cisco bug ID CSCeg71157.
The issue was first found in CiscoSecure ACS for Windows version 3.3.1. The issue is also seen with CiscoSecure ACS version 3.3.2.
When max sessions are configured for user settings or group settings to a value of 2 on the CiscoSecure ACS for Windows server using local database, more than two sessions are allowed.
If the max session in user setup or group setup is set to 1, CiscoSecure ACS for Windows allows only one user to log in. If it is changed to anything other than 1, as many users as desired are allowed to connect without restriction.
Resolution
For a workaround, download Cisco Secure ACS for Windows version 3.3.3.
If there are any problems with the software download, contact Cisco Technical Support.