Vacuum problem due to temp tables

Hi,

We were running full vacuum on DB when we encountered the error below;

INFO: analyzing "public.bkup_access_control"
INFO: "bkup_access_control": scanned 14420 of 14420 pages, containing
1634113 live rows and 0 dead rows; 30000 rows in sample, 1634113 estimated
total rows
INFO: vacuuming "pg_catalog.pg_index"
*vacuumdb: vacuuming of database "rpt_production" failed: ERROR: duplicate
key value violates unique constraint "pg_index_indexrelid_index"*
DETAIL: Key (indexrelid)=(2678) already exists.

The above table on which the error occured was actually a backup table of an
existing one.

JFI. The backup table was created by

SELECT * into bkup_access_control FROM access_control;

Details :

version

----------------------------------------------------------------------------------------------------------------------------------------
PostgreSQL 9.0.1 on x86_64-unknown-linux-gnu, compiled by GCC gcc (SUSE
Linux) 4.5.0 20100604 [gcc-4_5-branch revision 160292], 64-bit

Can you let us know the reason for this error?

Regards,
Bhakti