Nope. If you want to to have Kat in the game and collar Bree, do the whole gamer side until the quest moves to completed, then run the following command:
Code:
DONE.pop("bree_event_05")
This will reset her path and you can continue on the maid path while having Kat in the game. There's not much content with Kat in the game yet tho. The most you can get is a hot tub sex and threesome with bree but both of them require you to have sex with Kat first which you can't so you'll need to cheat that in either way.
So far nothing broke for me and I finished both Kat and Bree.
This might break on later updates when more content is added for either of them tho.