CREATE TABLE #TEST(ID TINYINT NULL, COL1 CHAR(1))
INSERT INTO #TEST(ID,COL1) VALUES (1,'A')
INSERT INTO #TEST(ID,COL1) VALUES (2,'B')
INSERT INTO #TEST(ID,COL1) VALUES (1,'A')
INSERT INTO #TEST(ID,COL1) VALUES (1,'B')
INSERT INTO #TEST(ID,COL1) VALUES (3,'C')
INSERT INTO #TEST(ID,COL1) VALUES (3,'C')
INSERT INTO #TEST(ID,COL1) VALUES (3,'C')

-- Step #1: Find and copy the duplicates to a temp table
SELECT * INTO #TempTable FROM #TEST GROUP BY ID, COL1
HAVING COUNT(*) > 1

-- Step #2: Delete the duplicates in the #TEST table
DELETE #TEST FROM #TEST, #TempTable
WHERE #TEST.ID = #TempTable.ID AND #TEST.COL1 = #TempTable.COL1

-- Step #3: Copy the duplicates and put it back into the original Table
INSERT #TEST SELECT * FROM #TempTable

-- Step #4: Drop the temp table
DROP TABLE #TempTable