Error by restoring postgresql database

[Udo Hillenbrand]

Hello,
I am dumping our database daily from sim by subject matter the document 'sim5.1_backup_restore.pdf'.
But when I restore the database:
/usr/bin/dropdb -p 5432 -h 127.0.0.1 -i -e insight_v1_0
/usr/bin/createdb -O postgres -h 127.0.0.1 -p 5432 -U postgres insight_v1_0
/usr/bin/psql -q -h 127.0.0.1 -U mxadmin -p 5432 -f /home/backup/saveHPSIMdb_20071010010002 -d insight_v1_0

following error occured:
"psql:/home/backup/saveHPSIMdb_20071010010002:320168: FEHLER: konnte Unique Index nicht erstellen
DETAIL: Tabelle enthält duplizierte Werte.
"

But the applikation of sim works fine after the restore!!!
Why I have the error of duplicate values?
I have droped the database and created a new db...

Thanks
kind regards

Udo Hillenbrand