How can i avoid that the quizz result is overwritten in case someone tries to re-take a test? Is it possible to store the results from a previous quiz so you can compare possible improvement.
-Yes, you can implement logic within you SCO to detect if it has been attempted before and previously recorded a score. In that case, you can either decide not to allow them take it again, or to allow it and score the second attempt appropriately. If you want to persist these attempts more permanently in a way that you can access, you might consider storing them each as an objective.