There are two ways to fulfill your needs:
1) Apply for an additional instance for CRM Online, import the customization and import data via following tool, then do the test.
Migrate data-Microsoft Dynamics CRM 2011 Instance Adapter
2) Create a case to Microsoft to get the data backup, import into CRM onpremise envirnment to do the test.
Microsoft is conducting an online survey to understand your opinion of the Msdn Web site. If you choose to participate, the online survey will be presented to you when you leave the Msdn Web site.
Would you like to participate?