Checksumpillar auditdb can have multiple id's for the same actor

The checksum pillar can fail in a way that results in an actor being inserterted more that excatly once in the Actor table of the audit database.
This seem to have happened when a database connection was lost.
This results in puts (perhaps other operations) failing since the code extracting the actor expects at most one result.
The solution is to put a unique constraint on the specific table, so the database it self will refuse to let one actor have multiple rows in the Actor table.