Hi,
If I understand the question, no, the images you store at Auctiva aren't actually hosted in two places.
If you relist, any links to stored images at Auctiva should continue to operate unless you delete the images stored at Auctiva. Note, a relist from eBay isn't tracked for image use by Auctiva, so don't use the Deletion Wizard or the images will potentially get flagged for deletion.
Danno