Note that sql server setup sets the server name to the computer name during installation. Change @@SERVERNAME by using sp_addserver and then restarting SQL Server.
With multiple instances of SQL Server installed, @@SERVERNAME returns the following local server name information if the local server name has not been changed since setup.
@@SERVERNAME function and the SERVERNAME property of SERVERPROPERTY function may return strings with similar formats, the information can be different. The SERVERNAME property automatically reports changes in the network name of the computer.
@@SERVERNAME does not report such changes. @@SERVERNAME reports changes made to the local server name using the sp_addserver or sp_dropserver stored procedure.