Section 1910.147 does not require that each authorized employee be issued a lock. Employers can either issue lockout/tagout devices to each authorized employee or maintain a supply and assign or distribute them as needed. This does not mean that all the locks can be opened with the same key. Employees who apply a lock must have the assurance that no other employee can remove it.
If an employer implements a system where employees may not always use the same lock, procedures must be in place to control who has keys to those locks. For example, a supervisor could keep the keys to shared locks and check-out/check-in the keys when authorized employees use them.