We upgraded to 6.0 mp6 on solaris for media and master server
yesterday.  We had the same with vault duplication.  I seen your message
of the Peer to Peer Newsgroups forum.  I post this there and emailing
what we found out last night.  I found on another site a workaround. 
According to the veritas forum it is a Solution from Symantec support:
 
Run "nbrbutil -dump" and analyze the output, looking for the "MDS
allocations in EMM" section. Find the allocation key for the tape that
is "in use".
 
Then run "nbrbutil -releaseMDS <allocation key #>".
 
The tape will now be released, and can be expired, moved, deleted, or
whatever you need to do with it. 
 

Here's the output of nbrbutil with no arguments (-help and -Q aren't
valid):
 
************
Arguments:
-dump -- dump all nbrb allocation and request list
-dumptables -- have nbrb log its internal state
-release <GUID> -- Release the allocation with the given identifier
-cancel <GUID> -- Cancel the allocation request with the given
identifier
-resetAll -- Reset all nbrb allocations, requests, and persisted state
-resetMediaServer mediaserver -- Reset all nbrb EMM/MDS allocations
related to LTID on the mediaserver
-listOrphanedMedia -- List media reserved in EMM but with no
corresponding allocation in RB
-listOrphanedDrives -- List drives reserved in EMM but with no
corresponding allocation in RB
-listOrphanedStus -- List storage units reserved in EMM but with no
corresponding allocation in RB
-releaseOrphanedMedia <name> -- Release media reserved in EMM but with
no corresponding allocation in RB
-releaseOrphanedDrive <name> -- Release drives reserved in EMM but with
no corresponding allocation in RB
-releaseOrphanedStu <name> -- Release storage units reserved in EMM but
with no corresponding allocation in RB
-releaseMDS <ID> -- Release EMM/MDS allocations by MDS allocation ID
-releaseAllocHolds -- Release allocation holds due to alloction errors
for drives/media
-suspend -- Suspend nbrb processing
-resume -- Resume nbrb processing
************* 
 
**URL got this from is:
http://forums.veritas.com/discussions/thread.jspa?threadID=61500&start=15&tstart=0