Why is a duplicate record inserted when it should not be? Why does this command

insert into "deliveryLog" select * from temp_dellog where "deliveryID" &lt; 15620652


give this output?

********** Error **********

ERROR: duplicate key value violates unique constraint "deliveryLog_pkey"
SQL state: 23505
Detail: Key ("deliveryID")=(15620652) already exists.


Both tables have identical structure, deliveryID is a bigint.
This turned out to be a red herring.  When pgadmin gets disconnected midquery, it returns the last error again even if it was an entirely different command! :)