Creating a copy of primary database and attaching the copy database in the same sql instance
IF the server is NOT a PRODUCTION server, then you can backup the databases you need for Data manipulation and restore them with databaseName_test.

Keep in mind that you will still be competing for resources on the server by creating another set of databases.

Why cant you install another instance of sql server ? Even the enterprise edition is free for 30 days (for evaluation purpose ONLY) or just buy a Developer edition which is much cheaper. If you have MSDN subscription, you will be able to get one. Windows Azure is also another option.

Below will give you the correct version and some more info :

     SELECT
   SERVERPROPERTY ('MachineName') AS PhysicalMachineName,
   SERVERPROPERTY ('ServerName') AS SQLServerName,
   SERVERPROPERTY ('Edition') AS ServerEdition,
   CAST(SUBSTRING(@@Version,charindex('SQL',@@version, 1),15) AS VARCHAR(255)) +  ' + ' 
       + CAST (SERVERPROPERTY ('productlevel')AS VARCHAR (50)) + ' + (Build'
       + CAST (SERVERPROPERTY ('ProductVersion') AS VARCHAR (50)) +')' AS ProductVersion,
    RIGHT(@@version, (Len(@@Version)-charindex('Windows',@@version, 1))+1) AS [O.S.],
 SERVERPROPERTY ('Collation') AS Collation