Well i don't think thats how it works the dog from little A's memories was an actual dog. While hybrid was once a human, not an actual animal to half human. So fluffy is most definitely not the dog. I think.
Okay but think of this in ch.11 Fluffy has a flash back to Mr.A because of Little A and in it, it shows Fluffy getting head patted As A Dog. Also he's the only one who acts like an animal 100% the rest talk and think what Little A and the chicken did sounds sus, vs Fluffy who didn't know at all and never talks he kicks little A to stop and when he gets him to help he picks him up instead of telling him they need help or to follow.
Also this is the first few chapters there could be different cases the Center doesn't know about, and if it's true Fluffy used to be a dog Mr.A probably kept it secret like he tried to do with the eggs.
I Honestly Thought Fluffy Was The Dog From Little A's Memories On The Farm Unc what the hell!?!?