void Main()
{
    DataTable dt = new DataTable();  
    dt.Columns.Add("DW",typeof(int));  
    dt.Columns.Add("DADUI",typeof(int));  
    dt.Columns.Add("PERSON");  
    dt.Rows.Add(1,2,"john");
    dt.Rows.Add(1,3,"jack");
    dt.Rows.Add(1,3,"tom");
    dt.Rows.Add(1,2,"jordan");
    dt.Rows.Add(2,3,"dennis");
    var result=from d in dt.AsEnumerable()
                group d by new {DW=d.Field<int>("DW"),DADUI=d.Field<int>("DADUI")} into g
                select new 
                {
                  DW=g.Key.DW,
                  DADUI=g.Key.DADUI,
                  PERSON=g.FirstOrDefault().Field<string>("PERSON")
                };
    DataTable dtNew=dt.Clone();
    result.ToList().ForEach(d=>dtNew.Rows.Add(d.DW,d.DADUI,d.PERSON));
     
}