Creating new SID’s on NT4.0 Clients

Over the past few years, my company has been “cloning” our Windows NT Workstation 4.0 clients. Using a tool from Sysinternals, I discovered that we have many duplicate SIDs on our NT4.0 Domain. That hasn’t been a problem with NT4; however, I understand it might be with an NT2000 Domain, which we will be moving to. Does anyone know if that is true?
Also, I have a tool that will allow me to change one workstation at a time, but does anyone know of a tool that will allow us to do multiple workstations at a time?