How to remove duplicate records from GridView in ASP.Net

I used this example http://www.aspsnippets.com/Articles/Paging-in-ASPNet-GridView-using-jQuery-AJAX.aspx

but add this in gridview

<asp:GridView ID="GridView1" Width="300" runat="server" AutoGenerateColumns="false" RowStyle-BackColor="#A1DCF2"
            HeaderStyle-BackColor="#3AC0F2" HeaderStyle-ForeColor="White">
            <Columns>
                <asp:TemplateField runat="server" HeaderText="Imagen">
                    <ItemTemplate>
                        <table>
                            <tr>

                                <td>......
                                </td>
                                <td>......
                                </td>
                                <td>......
                                </td>
                                <td>......
                                </td>

                            </tr>
                        </table>
                    </ItemTemplate>
                </asp:TemplateField>
            </Columns>
        </asp:GridView>

I should change  here so that records are not duplicated

var row = $("[id*=gvCustomers] tr table tr:last-child").clone(true);
$("[id*=gvCustomers] tr").not($("[id*=gvCustomers] tr:first-child")).remove();

Thanks!