[This is preliminary documentation and subject to change.]
RSM tracks duplicate copies of media only if they are all in an online library at the same time. Each medium is given a unique PMID and can be accessed by an application. For example, if a user has two copies of the Microsoft® Windows NT® Server installation CD-ROM and places both in a changer, RSM creates two PMIDs and tracks both media. When the CD-ROMs are ejected from the library, RSM continues to track both CD-ROMs. When one is inserted again, RSM will pick one of the PMIDs to use as the one that has been inserted.