Duplicate rows may exist in the cross reference table of an attributed relationship class

Description

An attributed relationship class uses a cross reference table to relate objects from two tables. In this table, each row holds the foreign keys to the two objects. There is no integrity check to make sure there is only one row for each unique combination of foreign keys. In other words, there can be two rows in the cross reference table with the exact same foreign keys.

Cause

This is currently by design.

Workaround