Locale.module: Can't add 3rd Language

I use the actual stable Version Drupal 4.6.5 with Postgresql and I can't add a third language for the Interface.

/admin/locale/language/add
query: INSERT INTO locales_target (lid, locale) VALUES (140,'it') in drupal/includes/database.pgsql.inc in Zeile 62.

I Think this bug comes from a wrong table definition in 'locales_target'.There is a UNIQUE KEY definded ( possibly cut and pasted from 'locales_source') with ONLY 'lid' as column.
But in my opinion it must be define 'lid' an 'locale' as a UNIQUE KEY, look please at the query.

-- copy from database/database.psql
CREATE TABLE locales_target (
...
--  UNIQUE  (lid)
  UNIQUE  (lid,locale)
)

Best Regards
Michael Klein