possible way to prove if butter and lesser are same or different morph?

I have seen lessers that look like really nice mojaves and mojaves that look like a dark, busy lesser. 'Normal' is not a simple gene. The version of normal that is combined with a lesser or mojave can greatly influence the look of the resulting offspring. For example, breeding lessers to reduced pattern normals has produced some really reduced pattern lessers, and breeding lessers to really dark normals with pronounced alien heads has produced busy dark lessers with lots of alien heads. Selective breeding can make a mojave much lighter and reduced as well. Over several generations you could produce a line that would be hard to distinguish from lessers.