I don't know what your intended degree is, but with some course combinations if you've been admitted for a joint honours degree, you have to take second year courses in one of the subjects in first year, followed by (the part that seemed a bit pointless to me) the appropriate first year modules in that subject in second year. This happened to me when I was admitted for joint honours English & Geography - I had to take the second year English courses in first year. The scary part was that nobody told me I was about to learn about Old English instead of nice fluffy poetry until I phoned up worried about clashes about a week before I was due to arrive (I think they're more organised these days since it warns you in the prospectus now). Despite this, and the usual first year settling in stresses, I had no problem with the material on the course (I had an A in Higher English and a B in the CSYS, and that background knowledge was more than enough to get through the course - nobody else on the second year course had done any Old English before either). It was also nice to know I was into honours in something before I started worrying about second year - it made dropping Geography in second semester a lot easier
So, a possible solution, if you feel you *really* want to do modules in two subjects whose first year courses are at the same time, might be to ask your advisor to change your degree intention to a joint honours in those subjects - although only if there is a joint honours course available with that combination of subjects. I don't know whether they'll let you do that, and it might depend on whether there are places available in the module in question (one of my friends had trouble getting into IR in first year four years ago because the subject was too popular that year and they only let people who had been admitted to that degree program into the class) but it might well be worth a try. It's usually fairly easy to change your degree intention in the Arts faculty (I lost track of how many times I changed between joint honours English/Geog, single honours Geog, and eventually, single hons English in first and second year) and you never know, you might enjoy your second subeject so much that you do end up taking it to honours.