I wouldn't say it is considered "cheating" if the professor is knowingly and willingly giving his students the same copy year after year. I think it is all in how you are using the material.. if you are just memorizing it to get an easy grade on the test, then yes, I consider that to be a form of cheating. However, if you are actually using it to actually study it and you are truly learning from it, then no. I just would be very careful and not memorize the exact format of the test, it would really be bad if you "memorized" the information instead of "learning" it and the test turned out to be entirely different.