Hi Miki,
To my knowledge, this is not how Moodle works. While there are many ways of creating duplicates of courses (using Import or upload courses + 'templatecourse' field being my favorites), there's no automated script updating the course content in copies when something is updated in the Master version of it.
One of the reasons why this should be avoided, in my opinion, is the fact that you don't swap textbooks or tests while your learners are using it, but instead modify your course content and layout after carefully evaluating it's last run. This prevents a lot of unrest among your teaching staff and students/learners.
Most activities (with completion enabled) for instance, are locked for any changes that might affect overall course completion for users. The questions associated with a quiz can't be modified in the quiz itself, in terms of text and answers after attempts have been registered for it.
That being said, you can duplicate a master course infinitely through Upload courses with a CSV that contains the 'templatecourse' field pointing to the master course's short name. Depending on how complex your master course is, this can be a bit of a stretch for most Moodle servers, but it is probably the best way of creating a large number of duplicates.