Restoring an existing installation of SQL Server with other active databases

For the purposes of disaster recovery, you should only restore to a new installation of SQL Server. However, you can restore an existing installation of SQL Server with other active databases. The server should be running the same version of Windows on the same hardware platform. It also should be running the same Service Pack level: the same version of SQL Server with the same service pack as the original server.

See Disaster recovery of SQL Server databases