窗口.用chrome打开可打开popus和新选项卡

我在chrome中遇到了一个奇怪的问题，我正在使用window.open打开一个新的选项卡，并使用tcpdf创建一个pdf，然后将其作为附件发送到特定地址，现在在chrome中将发送2封邮件。如果弹出窗口被启用，那么我得到2个窗口操作1。弹出菜单和2。新标签，首先我不明白这怎么可能，我从来没有见过。

如果是禁用弹出窗口，它只在新的选项卡中打开，但仍然有2封邮件。

下面提到了用于调用弹出页面和电子邮件代码的代码。请帮忙。

window.open('/loancal/rhexportemail.php' + qstring,"_blank");
//Code used to open popup 
//------------- EMAIL CODE ----------------//
$to = "someone@gamil.com";
$from = "info@mydomain.com";
$subject = "Loan Enquiry Calculation Cashback - " . $client;
$message = "Please find attached Loan Enquiry Calculation Cashback statement for ".$client."."  ;
//a random hash will be necessary to send mixed content
$separator = md5(time());
// carriage return type (we use a PHP end of line constant)
$eol = PHP_EOL;
// attachment name
$filename = $subject.".pdf";
// encode data (puts attachment in proper format)
$pdfdoc = $pdf->Output('LECC'.$separator.'.pdf', 'S');
$attachment = chunk_split(base64_encode($pdfdoc));
// encode data (multipart mandatory)
 $headers = "From: ".$from.$eol;
 $headers .= "MIME-Version: 1.0".$eol;
 $headers .= "Content-Type: multipart/mixed; boundary='"".$separator."'"".$eol.$eol;
 $headers .= "Content-Transfer-Enconding: 7bit".$eol; 
 $headers .= "This is a MIME encoded message.".$eol.$eol;
 // message
 $headers .= "--".$separator.$eol;
 $headers .= "Content-Type: text/html; charsrt='"iso-8859-1'"".$eol;
 $headers .= $message.$eol.$eol;
 // attachment
 $headers .= "--".$separator.$eol;
 $headers .= "Content-Type: application/octet-stream; name='"".$filename."'"".$eol;
 $headers .= "Content-Transfer-Encoding: base64".$eol;
 $headers .= "Content-Disposition: attachment".$eol.$eol;
 $headers .= $attachment.$eol.$eol;
 $headers .= "--".$separator."--";
 // send message
 if(@mail($to, $subject, $message, $headers))
 {
echo "<script type='text/javascript'> alert('mail sent');window.close();</script>";
 }
 else{
echo "<script type='text/javascript'>alert('mail not sent');window.close();  </script>";
  }