StephenWaite understood mt potentially confusing my question and answered it below.
multisite works like the default site
http://myhost/openemr/interface/login/login.php?site=default
with default changed to the name of your new site entered in the setup
each site will have it’s own users not connected in anyway to the other sites
it’s basically a really nice feature for hosting multiple practices with one code footprint and one database server