Finding duplicated values

I have a few tables that have duplicated values from an import from a
different database. I have two keys I tried to set as primary and got an
error
ERROR: could not create unique index
DETAIL: Table contains duplicated values.

Is there some join I can use to compare the hmhmkey, wmwmkey pairs against
the table to find duplicate values? Each pair key should be unique but the
old database was less than normalized.

I was trying to use the code below but it returned no rows.

SELECT hmhmkey, wmwmkey
FROM exceptions
EXCEPT
SELECT hmhmkey, wmwmkey
FROM exceptions;

Any suggestions?

Kent Anderson
EZYield.com
407-629-0900
www.ezyield.com

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