Avoid Duplicate Records In Crystal Report

DataTable  dtopdTreatment;
                string querysecond = "SELECT * FROM OPDPrescription AS opdPresc INNER JOIN content AS c ON opdPresc.contentid = c.id WHERE (((opdPresc.opdId)=" + id + ") AND ((opdPresc.[TypeOfTreatment])=1))";
                dtopdTreatment = da.GetDataTable(querysecond.Replace("'", "")).Tables[0];

              
                casereg.Subreports["RptTreatment"].Database.Tables["OPDPrescription"].SetDataSource(dtopdTreatment);
                 casereg.Subreports["RptTreatment"].Database.Tables["Content"].SetDataSource(dtopdTreatment);

                crpOPDCaseRegister.ReportSource = casereg;
                crpOPDCaseRegister.Refresh();
               
                dtopdTreatment.Clear();

I have Written Code Like Above
I am Using Crystal Report And and Dataset AS Datasource To bind To The Crystal Report.i am getting Duplicate Records in Crystal Reort.So How Can I Avoid The Duplication Of Records