Dedup CTE awesomeness

dedup.sql

WITH CTE (Colum1, Colum2, DuplicateCount)
AS
(
SELECT Colum1, Colum2, ROW_NUMBER() 
OVER(PARTITION BY Colum1, Colum2 ORDER BY Colum1) AS DuplicateCount
FROM MyTable
WHERE Colum1 = 1 AND Colum2 IS NOT NULL
)
SELECT * FROM CTE
WHERE DuplicateCount > 1