There are many ways to set up separate galleries, but Imagevue is not yet the multiuser gallery which you seem to be in need of. If you need everything separate, like contact forms and other settings, currently you would need to set up separate physical folders. If you want to use the same gallery location, this would work, but they would share some settings.
For example, you could create custom html documents, where you add some parameters directly to the html, for example "settings.email=
blah@blahblah.com" ... This would separate settings, in addition to the possibility of having separate content folders as explained in the links provided by Felix. You still need to create index files with custom settings manually though ...