SET NOCOUNT ON;
CREATE TABLE #t (
  product_name nvarchar(20), 
  vendor_name nvarchar(20)
)
GO
INSERT INTO #t (product_name, vendor_name) VALUES 
('SQL Server', 'Microsoft'),
('Oracle', 'Oracle'),
('DB2', 'IBM'),
('Oracle', 'Oracle'),
('Oracle', 'Oracle'),
('DB2', 'IBM'),
('DB2', 'IBM'),
('DB2', 'IBM');
 
SELECT * FROM #t;
 
DECLARE @col1 nvarchar(255), @col2 nvarchar(255), @dup_count int;
WHILE 1 = 1 BEGIN
  SELECT TOP 1 @col1 = product_name, @col2 = vendor_name, @dup_count = COUNT(1) - 1
  FROM #t
  GROUP BY product_name, vendor_name
  HAVING COUNT(1) > 1
  IF @@ROWCOUNT = 0 BREAK;
  DELETE TOP (@dup_count) 
  FROM #t 
  WHERE @col1 = product_name AND @col2 = vendor_name;
END
 
SELECT * FROM #t;
GO
DROP TABLE #t