I believe the test is graded along a curve based on test takers in the previous year. For example, in your score report it will list the average for examinations similar to yours in a previous time frame, not the examinations taken along with yours.
What this means in terms of repeat questions, I don't know, because obviously there has to be new questions from year-to-year. What I do know is that my score report showed the average from the previous year's examinations, and put my score in terms of SD and standard error from that average.