Whether the thesis defense can understand the manuscript is related to judging your teacher and the rules and regulations of the school. There is also an undergraduate thesis defense, and a master's degree is different from a doctor's degree. But it is generally allowed to see, but the impression should not be very good. Look at the manuscript to justify that you are not familiar with your paper at all, or have the meaning of plagiarism. It is not recommended that you look at the manuscript and reply.