Have denomralized data with duplicate data within a table.  Use a Common Table Expression or With clause to construct to constructive a recursive temporary referenced resultset from the original larger query source to return an in place grouped and distinct set that can then be counted and remove all the duplicate entries as follows

WITH cte AS (
SELECT <COLUMN_1>, <COLUMN_2>,
	ROW_NUMBER() OVER
	(
		PARTITION BY <COLUMN_1>, <COLUMN_2>
		ORDER BY <COLUMN_1>, <COLUMN_2>
	) row_num
FROM <TargetTable>
)
SELECT *
FROM cte
WHERE row_num > 1;