Hi Dave,
This may be a feature we add in the future, but currently there can only be one eBay account associated with each auctiva account
You could have two auctiva scrolling galleries on the same page if you copy/pasted the HTML for it from each auctiva account... or at the minimum, at least link to/advertise for eachothers stores on the About Us page or Blog in your Auctiva Store.
-- Auctiva David