Does Multi-DB create seperate user tables?

I have a project where we could create several hundred (say 250) eCommerce sites with about 1000 products and on average 3000 customers each. We were looking to do this as an MU installation since nearly all the sites would function identically. However, I'm not keen on sharing the user database across the sites as each one should be separate customer registrations. Does mutli-DB provide you separate user tables as well per site?