On Chrome only, there is the following HTTP error :

ERR_RESPONSE_HEADERS_MULTIPLE_CONTENT_DISPOSITION

For a file named "Ticket receipt, January 19", the "Content-Disposition" header is the following:

attachment; filename="Ticket receipt, January 19";filename*=UTF-8''Ticket receipt, January 19

It seems to be a known bug since Chrome 16 (https://productforums.google.com/forum/#!topic/chrome/H_DneQinvT0/discussion)