I think they are different lines of the same mutation. The different lines labeled calico have a lot of variation. The NWE line calicos could easily be mistaken for a Valentin line sugar. I have seen Sugars that look more calico as well. I believe that if you want to keep the caracteristics of a particular line, you have to be selective of any normals or morphs you breed them to. For example, I will breed my NWE line calico to a blackback because the blackback pattern is what drew me to the NWE calicos(I have a nice blackback lesser for her). I would do the same with a sugar as well, since they also have a strong blackback pattern.