I had a legion overseer on board, and then i used uther on brann bronzebeard in the tavern. Afterwards i played another legion overseer, but its buff was not applied to brann. It should have been a 17/16, but was a 15/15 instead. It also only showed a single instance of the overseer buff, but i dont know if thats correct. I have a screenshot of this, if someone can tell me how to upload the picture here i will.
https://drive.google.com/file/d/12BosOyy3lX5g2arEyQPEbc8qvpTI1Pyk
EDIT: screenshot now has notes