If a users' mail files was moved to a new Domino server. It is observed that the Server named in the location document is automatically updated to the new server, and the mail file name is changed to match the given user's mail file.
If a user has five location documents - - one for their own mail and four to access shared mail files (i.e. Sales, Info, Comments, Support) - - after we move the user to Mail01, all five location documents are set to the user's mail file.
In short, the idea is to retain the existing (shared) mail file specified in the additional location documents.