ORA-06502: PL/SQL: numeric or value

Sometimes you will see this error while doing duplicate database 

Oracle instance shut down
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of Duplicate Db command at 04/18/2017 13:10:23
RMAN-05501: aborting duplication of target database
RMAN-06136: ORACLE error from auxiliary database: ORA-06502: PL/SQL: numeric or value error

Recovery Manager complete.

Then connect to the source database and its catalog database. now unregister the unique name which you are going to re-use. In my scenario, I tried to duplicate the database as Testt13 and it's already exists.

rman target /
connect catalog rman/password@Rmancatalog

Recovery Manager: Release 11.2.0.4.0 - Production on Tue Apr 18 13:35:43 2017

Copyright (c) 1982, 2011, Oracle and/or its affiliates.  All rights reserved.

connected to target database: TESTPG (DBID=1734399999)
connected to recovery catalog database

RMAN> list db_unique_name of database;


List of Databases
DB Key  DB Name  DB ID            Database Role    Db_unique_name
------- ------- ----------------- ---------------  ------------------
5548648 TESTPG  1734399999       PRIMARY          TESTPG_DG1
5548648 TESTPG  1734399999       STANDBY          TESTT10
5548648 TESTPG  1734399999       STANDBY          TESTT13
5548648 TESTPG  1734399999       STANDBY          TESTPG
5548648 TESTPG  1734399999       STANDBY          TESTSG
5548648 TESTPG  1734399999       STANDBY          TESTPG_DG2

RMAN> resync catalog;

starting full resync of recovery catalog
full resync complete

removing the unwanted unique names

RMAN> unregister db_unique_name 'TESTT13';

database db_unique_name is "TESTT13", db_name is "TESTPG" and DBID is 1734399999

Want to unregister the database with target db_unique_name (enter YES or NO)? YES
database with db_unique_name TESTT13 unregistered from the recovery catalog

RMAN> unregister db_unique_name 'TESTT10';

database db_unique_name is "TESTT10", db_name is "TESTPG" and DBID is 1734399999

Want to unregister the database with target db_unique_name (enter YES or NO)? YES
database with db_unique_name TESTT10 unregistered from the recovery catalog

RMAN> resync catalog;

starting full resync of recovery catalog
full resync complete

RMAN> list db_unique_name of database;


List of Databases
DB Key  DB Name  DB ID            Database Role    Db_unique_name
------- ------- ----------------- ---------------  ------------------
5548648 TESTPG  1734399999       PRIMARY          TESTPG_DG1
5548648 TESTPG  1734399999       STANDBY          TESTPG
5548648 TESTPG  1734399999       STANDBY          TESTSG
5548648 TESTPG  1734399999       STANDBY          TESTPG_DG2

RMAN> exit



Now retry the duplicate it will work