Patch 12553054 : IBY : R12 : Unique Index IBY_USED_PAYMENT_DOCS_U1 cannot be created - table has dup

(Thread created by Oracle Support on behalf of Customer)
Hi there

We are not able to apply Patch 12553054:R12.IBY.B because of following error in the
Worker job 'ibydist.odf' :-

       Start time for statement below is: <Date> :  <Time>

      CREATE UNIQUE INDEX IBY.IBY_USED_PAYMENT_DOCS_U1 ON
      IBY.IBY_USED_PAYMENT_DOCS (PAYMENT_DOCUMENT_ID, USED_DOCUMENT_NUMBER)
      LOGGING STORAGE (FREELIST GROUPS 4 FREELISTS 4 ) PCTFREE 10 INITRANS 11
      MAXTRANS 255 COMPUTE STATISTICS  TABLESPACE APPS_TS_TX_IDX

      Statement executed.

      AD Worker error:
      The index cannot be created as the table has duplicate keys.

      Use the following SQL statement to identify the duplicate keys: