People often have the misconception that self cloning means the individuals look exactly alike to P1, when in reality coloration, pattern and growth may all be different. Parthenogenesis is not the same as artificial cloning, and thus people get confused.
In theory you could select the largest from each clutch in the line to enhance the bell curve, but in actuality I don't know. Marms are still a bit of a mystery. The nice thing is you should know pretty fast since they berry up usually by 2".