Joint degree??

http://www.qmul.ac.uk/undergraduate/coursefinder/courses/80068.html

Can someone explain this to me...when there are courses like 'English and Film Studies' (given a link to an example) 'History and Politics' etc and you get a choice on modules do you have to pick ones so that your course is 50:50? I would rather do a course that is 70:30 because I prefer one subject to the other but still want to both subjects.

Help