Operating on 2000\2003 network with same logins...

Is it harmful to have a few pcs setup for user with the same network login, would have thought it was ,from a housekeeping point of view, obviously with their profiles the same, have heard two different answers from two credible sys admins, one saying that its a bad idea , the other saying it doesn't matter as it is a network login, any links to a definitive answer would be appreciated..