[Description]
Reject duplicate appearances of columns in the referenced-columns list. Such a case is forbidden by the SQL standard, and even if we thought it useful to allow it, there would be ambiguity about how to match the list to unique indexes (in particular, it'd be unclear which indexopclass goes with which FK column).
[System Processing]
Processing will be aborted.
[Action]
To investigate the cause of the occurrence from the message, and remove cause.