Swapping rows between to and fro GridViews in ASP.Net

This way

<table border="0" cellpadding="0" cellspacing="0">
    <tr>
        <td style="width: 350px" valign="top">
            <asp:GridView ID="GridView1" HeaderStyle-BackColor="#3AC0F2" HeaderStyle-ForeColor="White"
                runat="server" AutoGenerateColumns="false" EmptyDataText="No records found">
                <Columns>
                    <asp:TemplateField>
                        <ItemTemplate>
                            <asp:CheckBox ID="CheckBox1" runat="server" />
                        </ItemTemplate>
                    </asp:TemplateField>
                    <asp:BoundField DataField="Id" HeaderText="Id" ItemStyle-Width="50" />
                    <asp:BoundField DataField="Name" HeaderText="Name" ItemStyle-Width="150" />
                    <asp:BoundField DataField="Country" HeaderText="Country" ItemStyle-Width="150" />
                </Columns>
            </asp:GridView>
        </td>
        <td style="width: 350px; padding-left: 5px" valign="top">
            <asp:GridView ID="GridView2" HeaderStyle-BackColor="#3AC0F2" HeaderStyle-ForeColor="White"
                runat="server" AutoGenerateColumns="false" EmptyDataText="No records found">
                <Columns>
                    <asp:TemplateField>
                        <ItemTemplate>
                            <asp:CheckBox ID="CheckBox1" runat="server" />
                        </ItemTemplate>
                    </asp:TemplateField>
                    <asp:BoundField DataField="Id" HeaderText="Id" ItemStyle-Width="50" />
                    <asp:BoundField DataField="Name" HeaderText="Name" ItemStyle-Width="150" />
                    <asp:BoundField DataField="Country" HeaderText="Country" ItemStyle-Width="150" />
                </Columns>
            </asp:GridView>
        </td>
    </tr>
</table>
<br />
<asp:Button Text="<<" runat="server" OnClick="TransferLeft" />
<asp:Button Text=">>" runat="server" OnClick="TransferRight" />

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!this.IsPostBack)
        {
            DataTable dt1 = new DataTable();
            dt1.Columns.AddRange(new DataColumn[3] { new DataColumn("Id"), new DataColumn("Name"), new DataColumn("Country") });
            dt1.Rows.Add(1, "John Hammond", "United States");
            dt1.Rows.Add(2, "Mudassar Khan", "India");
            dt1.Rows.Add(3, "Suzanne Mathews", "France");
            dt1.Rows.Add(4, "Robert Schidner", "Russia");
            ViewState["dt1"] = dt1;
            GridView1.DataSource = dt1;
            GridView1.DataBind();
        }
    }

    protected void TransferRight(object sender, EventArgs e)
    {
        foreach (GridViewRow row in GridView1.Rows)
        {
            if ((row.FindControl("CheckBox1") as CheckBox).Checked)
            {
                DataTable dt1 = (DataTable)ViewState["dt1"];
                DataTable dt2;
                if (ViewState["dt2"] == null)
                {
                    dt2 = dt1.Clone();
                }
                else
                {
                    dt2 = (DataTable)ViewState["dt2"];
                }
                DataRow dr = dt1.Select("Id = " + row.Cells[1].Text)[0];
                dt2.ImportRow(dr);
                dt1.Rows.Remove(dr);
                ViewState["dt1"] = dt1;
                ViewState["dt2"] = dt2;
                GridView1.DataSource = dt1;
                GridView1.DataBind();
                GridView2.DataSource = dt2;
                GridView2.DataBind();
            }
        }
    }

    protected void TransferLeft(object sender, EventArgs e)
    {
        foreach (GridViewRow row in GridView2.Rows)
        {
            if ((row.FindControl("CheckBox1") as CheckBox).Checked)
            {
                DataTable dt1 = (DataTable)ViewState["dt1"];
                DataTable dt2 = (DataTable)ViewState["dt2"];

                DataRow dr = dt2.Select("Id = " + row.Cells[1].Text)[0];
                dt1.ImportRow(dr);
                dt2.Rows.Remove(dr);
                ViewState["dt1"] = dt1;
                ViewState["dt2"] = dt2;
                GridView1.DataSource = dt1;
                GridView1.DataBind();
                GridView2.DataSource = dt2;
                GridView2.DataBind();
            }
        }
    }