I am using two surname. In my passport it is written as Sakshi Sung whereas in college it is Sakshi sharma. How should i proceed in future

I am interested in doing M S in electronic and Communication from Canada. Pls tell will there be any problem in getting admission in Canada/visa. What Surname should I mention at the time of appearing for GRE/IELTS. What kind of remidial action now I can take for the smooth admission in Canada