You cant accurately split the caps due to the fillers. I guess you could get the fillers out, but thats not really worth it.
You have to take either 10mg or 20mg. I have several bottles of Gaspari M1t & 10mg (all at once) has worked very well for me. I tried to increase to 20mg on my last cycle. The gains were not any better, but the cramping increased 10x. I dropped back down to 10mg after a few days. 10mg is plenty IMO.