Duplicate Animator Controller problem - models still using the previous controller


I have a problem with an AnimatorController. Here is a brief description of my project:

My character architecture is based on a Character script that has a Serialized AnimatorController field. The standard controller I set up is flexible and all my enemies, NPCs and the player use it. I wanted to mix things up a bit and add zombie type enemies and decided to create a new animator controller for that purpuse - only the controller would change and initially the scripts would run exactly the same.

I duplicated my standard controller (CTRL+D) to create the new UndeadAnimatorController, changed its name, inserted different animations to the existing states and when I rigged it to the Character script… well nothing happened really. Even though the inspector shows the character operates on the new controller all animations are played like in the old controller. I made a prefab of the new character, switched animations around, removed the controller etc. but I always get the animations of the original controller.

Can anyone explain what is causing this? Is duplication of the state machine not allowed and the only option is to create a new controller from scratch (possibly with different parameter names?). I know I am missing something and I cannot find any relevant information in similar topics.

Thanks in advance for any help.

Best regards

if you ever figure it out lemme know