Doesn`t make sense to me either ..... if the curl / density /colour of a stock is working for you, well, in many ways you`re lucky really....not having to make a template etc. and you can get a stock within a few days of needing one !
Taking the size of the average topper into account, the crown area is relatively large and there is usually a change of hair-direction there too [` Swirl` ] so it wouldn`t really be practical to incorporate two crowns into one topper on a custom-order, but I know sure feels wasteful to be cutting out a crown from a system and discarding the rest of it..... I wonder if you could send the front hairline area/s to some guys who might be wanting to experiment with front -partials.... could keep costs down a bit !