When you use random questions in a quiz and you duplicate the quiz, the new quiz random questions have the same reference than the old, so if you change the new quiz random category also change de old quiz random category.

To check it:
1. Create two question categories, “Category A” and “Category B”.
2. Create a quiz (Quiz 1).
3. Edit Quiz 1 and add one random question from “Category A”.
4. Duplicate this quiz and rename as “Quiz 2”. This quiz have one random question from “category A”.
5. Edit “Quiz 2” and click on the “Configure question” icon of the random question. Change the category to “Category B”.
EXPECTED: Quiz 2 take a random question from “Category B” and Quiz 1 take a random question from “category A”.
ACTUALLY: Quiz 2 and Quiz 1 take one random question from “category B”. Change in a quiz appears in the other.

I think that the two quizzes muss be independent. is is a problem because the change ocurred even when quizzes have attemps and it's difficult for the teacher to realize.

Thank you.