Duplication of improvised question

[osangoi]

Each time the Jazz Quiz in viewed in teacher mode a set of improvised question is addedd to the question bank. This cause a huge number of questions in the question bank.
The problem is in file view.php

/**
 * Entry point for viewing a quiz.
 */
function jazzquiz_view(): void {
    ...
    $iscapable = true;
    ...
    if ($iscapable) {
        if ($jazzquiz->is_instructor()) {
            $improviser = new improviser($jazzquiz);
            $improviser->insert_default_improvised_question_definitions();
        }