I have a gridview in which there are multiple rows with Edit options in each row. So what exactly the scenario is, whenever I click on EDIT button it will redirect me to next tab with the SAP ID of that row filled in the dropdownlist.

But currently what happening is, when I click the edit button for the first time, it shows only one value in the list,

but when I click second time, the list shows me two values. I dont want that, I want only the data value for which I have clicked the edit button.

Below is my GridView and ajax code for binding values

GRIDVIEW

<asp:GridView ID="grdSapDetails" runat="server" PageSize="10" AutoGenerateColumns="false">
                <Columns>
                    <asp:BoundField DataField="SAP_ID" HeaderText="Sap Id" />
                    <asp:BoundField DataField="SITE_NAME" HeaderText="Site Name" />
                    <asp:BoundField DataField="SITE_ADDRESS" HeaderText="Site Address" />
                    <asp:TemplateField HeaderText="Edit">
                        <ItemTemplate>
                            <input type="button" onclick='return HighlightTabFunction(this)' value="Edit" id="btnEdit" />
                        </ItemTemplate>
                    </asp:TemplateField>
                </Columns>
            </asp:GridView>

AJAX

function HighlightTabFunction(a) {
        var row = a.parentNode.parentNode;
        var rowIndex = row.rowIndex - 1;
        var SAPID = row.cells[0].innerHTML;
        $.ajax({
            url: "UBRDashboard.aspx/GETSTATEFROM_SAP",
            dataType: "json",
            type: "POST",
            contentType: 'application/json; charset=utf-8',
            data: JSON.stringify({ SAPID: SAPID }),
            async: true,
            processData: false,
            cache: false,
            success: function (r) {
                $('a[href="#tabs-2"]').click();
                var ddlSapID = $("[id*=ddlSapID]");
                ddlSapID.append($("<option></option>").val(r.d).html(row.cells[0].innerHTML));
                $("#hdnState").val(r.d);
            },
            error: function (xhr) {
                alert('Error while selecting list..!!');
            }
        })