Following query will help you to find out the duplicate values and their count in a column.
SELECT column_name, COUNT(*) Duplicates_Count
FROM [dbo].[table_name]
GROUP BY column_name
Following query will help you to find out the duplicate values and their count in a column.
SELECT column_name, COUNT(*) Duplicates_Count
FROM [dbo].[table_name]
GROUP BY column_name