Question about Good Job | Musashi's Way achs

[sm182]

Just wondering if these are stackable or do I need to do two seperate playthroughs as for some reason mine reverted to easy at some point.

[Ninja x360a]

Uhh. Well it says you completed this game now, but they are stackable, if you are wondering. haha Sorry for a delay, I dont always check the Ninja Blade forums.