Hello,
I accept. However, with Symantec incase you require older Definitions, you could either make sure you store with the proper settings on the SEPM, so that as and when required you could rollback to the older definitions.
Check this Articles:
How to Backdate Virus Definitions in Symantec Endpoint Protection Manager
http://www.symantec.com/docs/TECH102935
Disk Space Management procedures for the Symantec Endpoint Protection Manager
http://www.symantec.com/docs/TECH96214
Again, on the SEP clients, only 3 definitions would be stored by default.
Incase, you want the Older definitions (other than uploaded files on the FTP server) for testing purposes, then you may have to create a case with Symantec Technical Support.
Hope that helps!!