Interesting that you have this, too...we have been wondering similarly. Our slightly littler Yorkie has poopies about twice the size of our slightly bigger Yorkie...diameter and quantity. The doggies are not that much different in size or weight...1" diff in height (leg length) and .5" in neck and hip measurements...all else is the same...probably no more than .5 lbs diff between them. We have been seeing this "problem" since we got the second Yorkie in August and have finally decided their poopie sizes are just 'normal' for each of them...regardless of how odd it seems. Don't know if that helps...
- Cat