How to prevent the Price Update Batch duplicating items

SOLVED

I'm in the process of doing a large update of our prices and the test products so far have all been duplicated. I read the help article about how products with blank warehouses in the price list get duplicated. It seems all our products have this issue, is there a way to fix this across our entire range?

The article in question: za-kb.sage.com/.../viewsolution.jsp