In this case I would wait and see in another week or two which twin is the strongest twin. Then try to reroot the other smaller plant (probably won't work but it's worth a shot). They will both share the same root structures and compete for resources so you'll probably end up with 2 lower then they could be yields. If you separate and let the one thrive it will be able to produce like it wants to. Just my opinion though you could always just continue to wait and see what happens.