Both methods as suggested by Bob and Karthikeyan will work - only problem is that Karthikeyan does not even attempt to give sufficient info to a user that confesses to be new to NetBackup.
The method suggested by Karthikeyan is explained in the White Paper called
Recovery without Import.
Using this method, you need network connectivity between the 2 master servers.
On the 1st master, you will have to be able to identify the images that you want to copy. If it's a backup for a particular client on a particular date, copy the .../netbackup/db/images/
client/10...... folder to the 2nd master. If it's more than one client, you will also need to find the other client images. You also have to ensure that the tapes are write protected and added to a pool on 2nd master that will never be used for backups.
For an experienced user, method 2 is the quickest and easiest. For an inexperienced user, I'll recommend the 1st suggestion (to import).