Hello,
SEP 12.1 includes features and enhancements that greatly increase performance and security for virtual environments.
Usually, it is usually the same procedure which is followed for deployment.
However, there are few Best Practices and Recommendations which you may follow to get the best performance.
Check these Articles:
Using Symantec Endpoint Protection in virtual infrastructures
http://www.symantec.com/docs/HOWTO81060
Best practices for virtualization with Symantec Endpoint Protection 12.1.2
http://www.symantec.com/docs/TECH197344
Symantec Endpoint Protection 12.1 & Virtualization
http://www.symantec.com/docs/TECH194383
Secondly, In case if these machines are cloned, then there are few steps you may need to follow -
How to prepare a Symantec Endpoint Protection 12.1 client for cloning
http://www.symantec.com/docs/HOWTO54706
How to repair duplicate IDs on cloned Symantec Endpoint Protection 12.1 clients
http://www.symantec.com/docs/TECH163349
Hope that helps!!!