PHPMailer 5.1 sends duplicatie mails when adding more than 1 receiver
$mail             = new PHPMailer();
$mail->AddReplyTo("name@yourdomain.com","First Last");
$mail->SetFrom('name@yourdomain.com', 'First Last');

$mail->AddAddress("info@address.com");
$mail->AddAddress("info@address.nl");
$mail->Subject    = "PHPMailer Test Subject via mail(), basic";

$mail->Send();

$mail = new PHPMailer();

$mail->SingleTo = true; //will send mail to each email address individually


$mail->AddReplyTo("name@yourdomain.com","First Last");
$mail->SetFrom('name@yourdomain.com', 'First Last');

$mail->AddAddress("info@address.com");
$mail->AddAddress("info@address.nl");
$mail->Subject    = "PHPMailer Test Subject via mail(), basic";

$mail->Send();