mpdf backslash bug

test.php

<?php                                                                                                                   
                                                                                                                        
$html = '                                                                                                               
    <p>Here should be one: \\ and here should be two \\\\</p>                                                           
    <pre>Here should be one: \\ and here should be two \\\\</pre>                                                       
';                                                                                                                      
include("MPDF53/mpdf.php");                                                                                             
$mpdf=new mPDF();                                                                                                       
$mpdf->WriteHTML($html);                                                                                                
$mpdf->Output();                                                                                                        
exit;