Audit Handling of Changes to Primary and Unique Key Values

If a value changes in a column that is part of the table's primary or unique key, Oracle inserts two new rows in the shadow table, one with a transaction type of Delete (D) and one with a transaction type of Insert (I).

For example, because the STATUS_RC column in the CDR_ROLES_B table is part of the unique key, whenever you modify a role there is a change to a unique key column and the system adds two rows to the shadow table, one to delete the old record and another to insert the new one.