In SAP previous version you can use same user for concurrent login , but from SAP version 9 it has been restricted due to the license abuse prevetion for more information check the following note....
SAP Note 1815509 - "License Abuse Prevention" mechanism in SAP Business One 9.0.
1810895 - License error: Your session has been locked because another session was started using the same user ID
Hope helpful :smile:
