[Milhouse]

Two different databases accessed by the same client isn't possible (unless you use profiles, which might work, one database per profile).

But if what you want to do is have your XBMC clients access all of the media stored on the two different NAS devices, then that's entirely possible with a single MySQL database. Just add both NAS as sources on your clients (or just the scraper client), then scrape in the content to your single MySQL database. Add the MySQL database settings to the advancedsettings.xml on each client, which should then have access to all the media on the two NAS devices.