Did they require a thumbprint on the exam? Did you write all of the written assignments as well so that your handwriting would match?
More seriously, it seems like it would be hard to pull off in a small course where the instructors might recognize the students.
2. No one remembers students’ handwriting.
3. In our system professors only read lectures before large groups of students. They have “docents” (not sure what’s English word for that) who do smaller practical classes professors were taking the exams. Also, some of them passingly saw my face in the hall. Once or twice I got by mistake to my former professors - the company had to fix the issue (with money)