PIWIK 1.3 db upgrade problem - SQLSTATE[42000]

Hello - i get the following error when trying to update piwik from latest to 1.3.

Kritischer Fehler während der Aktualisierung:
Error trying to execute the query ‘ALTER TABLE piwik_log_visit
ADD INDEX index_idsite_idvisitor (idsite, idvisitor)’.
The error was: SQLSTATE[42000]: Syntax error or access violation: 1061 Duplicate key name ‘index_idsite_idvisitor’

Someone got an idea?

Since 1.2 the automatic update doesnt work anymore - at the last upgrade version i had to work in phpmyadmin too.

Greetings from Germany

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