I just racked a cider that has been sitting in primary for a month and a half. It smelled sulphury so I racked it to another carboy. This cider had Wyeast Sweet Cider yeast. There was a lot of room in the top of the carboy so I racked about a gallon of another completely fermented cider on top, this one had a Wyeast German wheat yeast. Did I mess anything up? I figured that since both the ciders reached their final gravities that it shouldn't be a big deal. I was going to just pour a gallon of fresh apple juice on top but I didn't want it to start fermenting again.