I read a question Question Banks creating multiple IDs for same question that was posted July 2016. Has this been resolved? If no, might it be the cause the following problem?
I had four Question Banks (Ch1, Ch2, Ch3, Ch4). Each bank contained 10 different questions. While setting up a 20 question Quiz, I asked the system to randomly pull 5 questions from each of these Question Banks. When students took the Quiz, some received duplicate questions from within a bank. For example, one student received a duplicate question from the Ch2 bank, another student received a duplicate question from the Ch3 bank, and another student even received 2 sets of duplicate questions (1 duplicate from the Ch1 bank and 1 duplicate from the Ch2 bank). I have run into this a couple of times, so have stopped using Question Banks in this way.