Vacuumdb error

Dear List,

Today morning at 01:00 AM in our PostgreSQL 9.0.3 server a routine
maintenance script has started (vacuumdb --all --full --analyze), and
stopped with this error:

sqlstate=23505ERROR: duplicate key value violates unique constraint
"pg_index_indexrelid_index"
sqlstate=23505DETAIL: Key (indexrelid)=(2678) already exists.

We didn't do or change anything in postgre enviroment (except we raised the
max_lock_per_transaction from 64 to 128)

I've started a search on the internet, because of this error, but I didn't
find anything, that I can use. Any idea? I've checked the postgres DB /
catalogs / pg_catalog / tables / pg_index, and there is the record where
indexrelid=2678, but there is only one record there...

I saw, that somebody has the same problem (with the same ID!), and Tom Lane
and Robert Haas requested the (select ctid,xmin,xmax,* from pg_index;) query
output in a file. See attached.

PostgreSQL: PostgreSQL 9.0.3 on i386-portbld-freebsd8.2, compiled by GCC cc
(GCC) 4.2.1 20070719 [FreeBSD], 32-bit

Thanks, and regards,
Carl