functions_session_data.asp error with v9.67

As an attempt to minimize our sessions drop-outs and as suggested here i did enabled database session storage. Along with this i have enabled logging as well and found the following error occurring

Guest - ERROR - File: functions_session_data.asp - Error Details: err_SQLServer_getSessionData()_save_new_session_data - Microsoft OLE DB Provider for SQL Server - Violation of PRIMARY KEY constraint 'PK__tblSession__11D4A34F'. Cannot insert duplicate key in object 'dbo.tblSession'.

All errors are reported for guest account only.

any advice on how to handle this.

thank you !