I know exactly what you're talking about, unfortunately the only way is the way that you are already doing it, Vue is trying to out-think you by assuming that you want to make that other zone the same material as the first zone (which in some instances you might want to do but not in this instance). Without making the material from scratch again or as dlk30341 suggested and edit the material in the object tree instead of using the material summary (which I'm assuming you're using since the object has different materials applied to the same mesh) the only way to do it is the way you're doing it, I've been doing the same thing for a while now and though irritating it's just learning to work around one of Vue's "Features".