By default, SAP users can have a multiple logons to SAP system but we can disable the function. If the function is disable, multiple dialog logons to (in the same client and under the same user name) are blocked by the system: When the system recognizes a multiple logon, it displays a dialog box with the options “Terminate the current sessions” or “Terminate this logon”. This parameter works with SAPGUI logons.
1. Go to RZ10. Select the Instance profile, choose Extended maintenance and create a new parameterlogin/disable_multi_gui_login (if it’s not created yet)
2. Create a new parameter login/disable_multi_gui_login and set the login/disable_multi_gui_login=1. This option will controls the deactivation of multiple dialog logons
3. You also can allow certain users to have an ability to have a multiple logons. At RZ10, within the same instance profile. Put below parameter:
Each username is separated by comma and do not leave space between the username. Finally*, restart* the Instance to apply these changes.