The man page is your friend:

bpduplicate: [-dstunit <destination storage unit
label>][,<stunit-copy2>,...,<stunit-copyn>]]
    [-p] [-pb] [-PM] [-PD] [-v] [-local] [-client <name>]
    [-Bidfile <file_name>]
    [-st <sched_type>] [-sl <sched_label>] [-L <output_file> [-en]]
    [-dp <destination pool name>[,<poolname-copy2>,...,<poolname-copyn]]
[-shost <source host>]
    [-policy <name>] [-s mm/dd/yyyy HH:MM:SS] [-e mm/dd/yyyy HH:MM:SS]
    [-pt <policy_type>] [-hoursago <hours>]
    [[-cn <copy number>] | [-primary]]
    [-M master_server] [-altreadhost <hostname>]
    [-backupid <backup_id>] [-id <media_id>]
    [-rl <retention_level>[,<rl-copy2>,...,<rl-copyn>]]
    [-fail_on_error <0 | 1>[,...,<0 | 1>]]
    [-mpx] [-number_copies <number>]
    [-set_primary <copy_index>

You want the "-rl" option:

 -rl retention_level[,rl-copy2,...,rl-copyn]
         Provides a retention level for  each  copy  speci-
         fied.

         If no retention levels are specified, the  expira-
         tion  date  of  the original copy is used for each
         copy. If a  retention  period  is  indicated,  the
         expiration  date  for  the copy is the backup date
         plus the retention period.

         For example, if a backup was created  on  November
         14,  2003,  and  its retention period is one week,
         the new copy's expiration  date  is  November  21,
         2003.

          A value of -1 indicates that the original  expira-
          tion date is used for the copy.

-----Original Message-----
From: veritas-bu-admin AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-admin AT mailman.eng.auburn DOT edu]On Behalf Of Atif Munir
Sent: Wednesday, November 30, 2005 5:28 AM
To: veritas-bu AT mailman.eng.auburn DOT edu
Subject: [Veritas-bu] bpduplicate


I am duplicating some backup for off site and want to change the
retention. Is there a way that i can do it by using the bpduplicate
.....I am not interested to do it by using the bar code neither by
using the backup job id....may i have some switch of bpduplicate while
doing the duplicate.

_______________________________________________
Veritas-bu maillist  -  Veritas-bu AT mailman.eng.auburn DOT edu
http://mailman.eng.auburn.edu/mailman/listinfo/veritas-bu