There are a couple of interpretations to your question, so I will try to answer both:
1. You want to have more than one galleries stored in the same database. You can do this, just be sure that you choose a different database prefix for each gallery.
These galleries may be hosted in the same domaine by putting them in different subfolders within the domaine. Alternatively you can create subdomains on your domaine and point each to a different gallery.
2. You want to consolidate several galleries into one "home". In the nightly build there are a couple of examples of "super galleries" which are galleries whose content is other galleries.
Hope this helps. If not, give us the "more explaination..."