Great answer! You talked in technical terms, i explained why we can have more than one entry in terms of functionality as explained here. I will merge both answers. :D

` It is possible (but unusual) to have more than one record in the password file with the same user ID, thus permitting multiple login names for the same user ID. This allows multiple users to access the same resources (e.g., files) using different passwords. The different login names can be associated with differ- ent sets of group IDs. `