Ok, here is a cleanly installed NetBackup 5.1 installation.
Next, it was patched to 5.1 mp4, yeah 5.1 mp5 is out, but I am using mp4.

        NB_51_4_M *
        NB_CLT_51_4_M *
        NB_DMP_51_4_M
        NB_JAV_51_4_M *
        NB_ORA_51_4_M *
        NB_VLT_51_4_M

Patching complete.

As you can see, it does not have any of my policies.

logbash-2.03# ./bppllist
template_normal
template_weekend
logbash-2.03#

Okay, now, when I was running 6.0MP2, I ran the following command:
logbash-2.03# /usr/openv/netbackup/bin/admincmd/bpbackupdb -dpath /local/catalog

Now I am using:
logbash-2.03# cat /usr/openv/netbackup/bin/version
NetBackup-RedHat2.4 5.1MP4

Now, does a restore from 6.0MP2 to 5.1MP4 work?
Lets find out.

logbash-2.03# /usr/openv/netbackup/bin/admincmd/bprecover -dpath
/local/catalog -r ALL
Recovering test-backups-1001:/usr/openv/netbackup/db
Recovering test-backups-1001:/usr/openv/volmgr/database
Recovering test-backups-1001:/usr/openv/var/auth
Recovering test-backups-1001:/usr/openv/var/vxss
Recovering test-backups-1001:/usr/openv/var/license.txt
Recovering test-backups-1001:/usr/openv/var/license.txt.pre.5.1
Recovering test-backups-1001:/usr/openv/var/global
Recovering test-backups-1001:/usr/openv/var/authorize.txt
# note, I deleted the FQDN in the following lines and named it test-backups-1001
Recovering test-backups-1001:/usr/openv/db/data/NBDB.db
Recovering test-backups-1001:/usr/openv/db/data/EMM_DATA.db
Recovering test-backups-1001:/usr/openv/db/data/EMM_INDEX.db
Recovering test-backups-1001:/usr/openv/db/data/vxdbms.conf
Recovering test-backups-1001:/usr/openv/var/global/server.conf
Recovering test-backups-1001:/usr/openv/var/global/databases.conf
Recovering test-backups-1001:/usr/openv/db/data/NBDB.log
logbash-2.03#

Ok, now the moment of truth, does it see my polices?

logbash-2.03# /usr/openv/netbackup/bin/admincmd/bppllist
ARCH-NO-ITC-SUG-TEST
RMAN-NO-ITC-SUG-TEST
fs_test
master_test
master_test_multiplex
rman_test
template_normal
template_weekend
logbash-2.03#


Yes it does!

You can revert back from 6.0MP2 to 5.1MP4, very nice.

Justin.