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

Question

Why does this command

insert into "deliveryLog" select * from temp_dellog where "deliveryID" < 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.

Answer 1

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! :)