Well it also depends of the university... École d'Ingénieurs (Engineering Schools, it's a bit different from the american system) tend to be stricter about that

Well it also depends of the university... École d'Ingénieurs (Engineering Schools, it's a bit different from the american system) tend to be stricter about that while universities in France are less strict. I know for a fact that no exam were reused because the previous years exams were available at the library for students who wanted to study... Since most of the exams were open book, with a world problem to solve in about 3 hours, they were actually fun to study from.