Why does CORE display two names for a contact?

When setting up your Contacts such as Employees or Clients, you are asked to provide a Name and a Display As name. You can set these names to be same or slightly different, however, while name can be duplicate, the display name has to be unique (alphanumeric characters). Generally, CORE uses the Display As name in drop-downs, but in some cases, such as the Project Manager drop-down, it displays the Name field.