After editing participant, a record is added in civicrm_note in stead of updated

When I edit the participant from a contact for an event, I can find two records for the same entity_id (= id in table civicrm_participant) in the table civicrm_note. Thus in stead of updateing the note, a record is added.
I mentioned it because when exporting a list of participants, the record was added two times in the list (Excel) with the same data for all fields except the note.
So I think somewhere an sql-statement must change from INSERT to UPDATE.
This was the case in 2.1 and also in the new 2.2.

The last records in civicrm_note:
552 civicrm_participant 70 vierde keer 6 2009-03-17 NULL
551 civicrm_participant 70 NULL 6 2009-03-17 NULL