How to do a multiple print of crystal report in ASP.NET

protected void Page_Load(object sender, EventArgs e)
        {
            try
            {
                Session["pager"] = ((DataTable)Session["table"]).Rows.Count;
                rptDoc.Load(Server.MapPath(Session["path"].ToString()));
                string aaa = Session["path"].ToString();
                rptDoc.SetDataSource((DataTable)Session["table"]);
                reportViewer.ReportSource = rptDoc;
                reportViewer.RefreshReport();
                if (!IsPostBack)
                {
                    Session["index"] = 1;
                    lblback.Text = Session["back"].ToString();
                }
            }
            catch (Exception ex)
            {
                error.ErrorLogs(Session["UserName"].ToString(), url, ex);
                ScriptManager.RegisterClientScriptBlock(this, this.GetType(), "alertmessage", "alert('" + ConString.ErrorMessage() + "')", true);
            }
        }

<input id="btnPrint" type="button" value="Print" onclick="Print()" />

<div id="dvReport">  
                <CR:CrystalReportViewer ID="reportViewer" runat="server" AutoDataBind="true"
                    BestFitPage="False" EnableDatabaseLogonPrompt="False" EnableParameterPrompt="False" PrintMode="ActiveX" HasGotoPageButton="False" HasPageNavigationButtons="False" />
            </div> 

<script type="text/javascript">
    function Print() {
            var dvReport = document.getElementById("dvReport");
            var frame1 = dvReport.getElementsByTagName("iframe")[0];
            if (navigator.appName.indexOf("Internet Explorer") != -1 || navigator.appVersion.indexOf("Trident") != -1) {
                frame1.name = frame1.id;
                window.frames[frame1.id].focus();
                window.frames[frame1.id].print();
                
            }
            else {
                var frameDoc = frame1.contentWindow ? frame1.contentWindow : frame1.contentDocument.document ? frame1.contentDocument.document : frame1.contentDocument;
                frameDoc.print();
            }
        }
</script>

protected void btnPrint_Click(object sender, EventArgs e)
       {
           Session["pager"] = ((DataTable)Session["table"]).Rows.Count;
           rptDoc.Load(Server.MapPath(Session["path"].ToString()));
           string aaa = Session["path"].ToString();
           rptDoc.SetDataSource((DataTable)Session["table"]);
           reportViewer.ReportSource = rptDoc;
           reportViewer.RefreshReport();

           PrinterSettings printerSettings = new PrinterSettings();
           PrintDocument localPrinter = new PrintDocument();
           printerSettings.PrinterName = localPrinter.PrinterSettings.PrinterName;
           rptDoc.PrintToPrinter(printerSettings, new PageSettings(), false);
       }

PrintDocument localPrinter = new PrintDocument();