The command to list images in NetBackup is /usr/openv/netbackup/bin/admincmd/bpimagelist. The -L option will display the number of copies for each image.
To specify a particular image, you can use the -backupid option or the -client option with the -d
Some examples are:
/usr/openv/netbackup/bin/admincmd/bpimagelist -L -backupid testbackup_123456
or
/usr/openv/netbackup/bin/admincmd/bpimagelist -L -client testclient -d 11/20/2010 12:00:00 -e 11/21/2010 12:00:00