Print module download pdf file name change characters into HTML entities
I am not a specialist of dompdf, but having used fpdf, I think it's something you do in your print template or custom module that converts the fields in dompdf format. 
You may need to set a php rule like this: 

$title = mb_convert_encoding($title, 'HTML-ENTITIES', 'UTF-8');


Source: https://stackoverflow.com/questions/16384517/dompdf-character-encoding-utf-8

Or another one like this:

$titlePrintFriendly = preg_replace('#&amp;amp;#',chr(38),$title);


and then print $titlePrintFriendly

I used the second one in the past to trick printing some special chars.
The dompdf library should be loaded in the file you add this line.

I took the char number from https://github.com/dompdf/dompdf/blob/master/lib/fonts/Symbol.afm