Monday is the day….sunday is poop day, double the prep as last time…

This is my fifth colonoscopy, having had colon cancer, which was removed surgically in 2017. My question is how much miralax do you do with your prep, and why the varieties? Mine has always been 288g with 64 ounces of water. (Plus 4 ducolax) I lost the sheet the doc gave and googled miralax preps and came up with that same number. But today I found my instructions and saw it’s 510g with 128 ounces! (The dulcolax is the same). My doc has always told me my results were very clean and all was good, I wonder why the change. I’ll of course do as told and ask Monday, but curious what others are instructed.