If a photograph was previously registered inside of a collection or a group, and has now gained independent success, should the image be re-registered as a single work to maximize the benefits of registration?
As a general rule, the Copyright Office can issue only one registration for a work. For example, once a photograph has been registered within a group registration of published photographs, it cannot be registered again individually. There is a limited exception to this rule when works are registered when they were unpublished, as in an unpublished collection. In such cases, the works may be registered again after they have been published, but this is not necessary for copyright protection. Once a work has been registered in unpublished form, the registration will remain in effect even after the work is published.
Rob Kasunic, Director of Registration Policy and Practices at the U.S. Copyright Office