SELECT t.col0, t.col1, t.col2, t.col4
FROM mytable as t
  JOIN (
    SELECT col0, col1, col2, min(col4)
    FROM mytable
    GROUP BY col0, col1, col2
    HAVING COUNT(*) > 1
  ) as tmp ON
    tmp.col0 = t.col0
    AND tmp.col1 = t.col1
    AND tmp.col2 = t.col2
    AND tmp.col4 <> t.col4