Content Egg

Hi, I’m using Wp all import with your content egg addon to import product feeds directly into content egg from an xml file. Everything works fine but there is an issue I can’t resolve:

if I import an offer for a product and then decide to manually delete it from the product page this offer remains stored somewhere in the database. When I use wp all import again to add another offer to the same product the old offer shows up again. Is there a way to prevent this from happening ?