Is it possible to create learning process where participant can join only one ILT session?

Summary

We arrange a lot of internal training sessions (ILT) to our employees. Managers enroll employees to ILT sessions. We need to find a way to register learner to only one session.

Content

Is it possible to create a course or spezialisation where we have one course with one offering with multiple similar sessions (ILTs)? From activities manager chooses one session and enrolls learners to it. After completion of this one session course will be marked as completed. All sessions are exactly the same content wise so there is only need for one session per learner. Now managers and employees seem to be able to register on all sessions available on the course. We need to limit that to only one; manager registers employee and then there is no other ILT sessions possible