Oracle RAC backup

altnames folder plus files underneath the folder must be created manually. 

More information about this directory and files can be found under this topic in the same manual:
Redirecting a restore to a different client 

client_name is the name of the client from where the restore will be attempted.
The hostname inside the file is the hostname of Client for which backups were taken (the name in Clients tab of the Oracle policy).

failover_vipname is the same as vipname. This is the Virtual hostname associated with the Oracle Instance.

Have a look at these TNs as well:

NetBackup for Oracle image catalog configuration for RAC 
http://www.symantec.com/docs/HOWTO89692 

Steps needed to restore an Oracle Real Application Cluster (RAC) database that has been backed up via multiple node names
http://www.symantec.com/docs/TECH43187 

PS: 

Correct location of NBU manuals: 

NBU 7.0 Documentation: http://www.symantec.com/docs/TECH126327

NBU 7.1 Documentation: http://www.symantec.com/docs/TECH154178

NBU 7.5 Documentation: http://www.symantec.com/docs/DOC5138

NBU 7.6 Documentation:  http://www.symantec.com/docs/DOC6488