What common mistake is the user making in the provided PHP code that is causing the phpmailer to send emails twice?

The common mistake in the provided PHP code that is causing the phpmailer to send emails twice is that the code is calling the `send()` method twice. This results in the email being sent twice. To solve this issue, simply remove the extra call to the `send()` method.

// Create a new PHPMailer instance
$mail = new PHPMailer;

// Set up the email parameters
$mail->setFrom('from@example.com', 'Your Name');
$mail->addAddress('recipient@example.com', 'Recipient Name');
$mail->Subject = 'Subject of the email';
$mail->Body = 'Body of the email';

// Send the email
$mail->send(); // Remove this line if it is duplicated