Would very much depend on what you're studying, what you're wanting to study and your university's policies. Some degrees have a big overlap and it's possible to swap between them quite seamlessly. Sometimes you would be allowed to go into second year of an unrelated degree if you had good grades and could demonstrate you had caught up with the prerequisite material. The best thing to do is get in touch with your uni (you should have a personal tutor/mentor/advisor or something?) and ask whether it's possible. The worst that can happen is they say no!
Dan
Data Science, MSc @ HWU