Ill say it again....Though it's minor, they are not the same in terms of nutrition. Especially when feeding adult rats vs adult mice. BUT to state the point that there's no need to feed multiples of mice is logical.
https://www.rodentpro.com/qpage_articles_03.asp
Different fat percentages, protein, crude matter. I listened to an hour conversation about this from the person who produced my female JCP....and he happens to be the head zookeeper of reptiles at the Santa Barbara zoo. Once again, minor differences....but there are differences.