Alex,
The simple answer is this: If you are taking both short quizzes and then also full-length exams there is no way that you can avoid seeing the same questions questions on both sides.
The PM Exam Simulator has a single question pool of 1,600+ questions for the PMP exam. We have developed the questions in such a way that you end up with 7 exams that follow the PMP exam content outline perfectly (= correct distribution of questions per Domain) and 1 exam contains only ITTO questions. So you can -- if you want to -- take 8 full-length exams.
But many students have a hard time finding 4 hours at a time to take a full exam. That is why we also have the short quizzes. Here a student can, for example, ask the simulator to create a 30-question quiz that contains only questions from Scope Management. This is helpful if you just finished your studies on Scope and want to test yourself. But again... the simulator takes these 30 questions randomly from the pool of 1,600 and you will see these questions again once you start taking full-length exams.