column value bind twice in dropdownlist..

Question

column value bind twice in dropdownlist..

binded a dropdowlist[continents] with gridview.. but continents appear twice in dropdownlist..

ex: asia asia

        DropDownList1.AppendDataBoundItems = true;

        //  String strConnString = ConfigurationManager

        //    .ConnectionStrings["conString"].ConnectionString;

        String strQuery = "select ID, ContinentName from Continents";

        SqlConnection con = new SqlConnection(str);

        SqlCommand cmd = new SqlCommand();

        cmd.CommandType = CommandType.Text;

        cmd.CommandText = strQuery;

        cmd.Connection = con;

        try

        {

            con.Open();

            DropDownList1.DataSource = cmd.ExecuteReader();

            DropDownList1.DataTextField = "ContinentName";

            //DropDownList1.DataValueField = "Id";

            DropDownList1.DataBind();

        }

        catch (Exception ex)

        {

            throw ex;

        }

        finally

        {

            con.Close();

            con.Dispose();

        }

    }

    protected void Button1_Click1(object sender, EventArgs e)

    {

        SqlConnection con = new SqlConnection(str);

        SqlCommand cmd = new SqlCommand("select * from NEWS where CONTINENT = '" + DropDownList1.SelectedValue + "'", con);

        SqlDataAdapter Adpt = new SqlDataAdapter(cmd);

        DataTable dt = new DataTable();

        Adpt.Fill(dt);

        GridView1.DataSource = dt;

        GridView1.DataBind();

        Label1.Text = "record found";