It depends how you use it.
1. You can have two versions of database so that you can use one connection for one set of users and another connection to another set of users.
e.g. User A is a high priority user and may not afford slow reports due to database load, so you can have copies source DW, one being used only for particular set of users.
Using, replacement conncection you can define a new connection to a another DW when particular user is logged in.