Gauge is the key here. Peruvia is bulky and Patons Classic Wool is worsted. If it were a sweater you might have some issues, but since it's a bag the most that will happen is it'll be a different size. In this case the bag will be smaller. You could double it, but it would be more than bulky in which case the bag would be larger. Make sure you adjust needle size accordingly whichever you choose.
When asking questions ALWAYS post the name and a link for the pattern if you have it.