Well -er - they shouldn't be doing this. Once they are enrolled on it they should just be able to enter it each time. Or are you saying that they are creating themselves new logins and then enrolling in a course as a different/new student? In which case I would think again about having email-based self registration (if that is what you have) Could you give a few more details about what your students are doing and what your enrolment system is?
We are kind of wondering the same thing. We offer courses that an organization can purchase for their employees. If we give them an enrollment key, what’s stopping them from giving that key to more employees than what they paid for? We would have to continuously monitor for this. Is there an easier way to enroll larger groups like this?
If the organisation pays in bulk for the employees then you could get their names and details and upload them directly into the course via a flat file - have a look in the Moodle docs for upload users via flat file
Can the upload process be automated in some way?