I'll admit I noticed this bug months ago but I wasn't sure how to word it so I never made a thread about it. And maybe a thread already exists for this, I apologize if that's the case. (edit: I did find this in the bug index after making this, my bad!) But as the hunting holiday comes back around I find this bothering me again.
When you click the "select wolf" menu in hunting, I believe that if a wolf has already been selected for a different hunting trip, it's not supposed to show up in the list. But there is a bug where if you click to a different den in that menu, all of the wolves in all dens show back up.
As an example, my wolf Perle is currently on a hunting trip, and he is in my first den. So when I initially open the menu, he isn't there. But if I click on a different den in that menu then click back to the first one, Perle is visible again, and I'm able to select him. If I try to do the hunt with him, it says "You cannot use a wolf that is already hunting."
Because of this bug, all wolves will always be visible in any den after the first one. If you never use a wolf from your first den for hunting, or never click back to the first tab after click to a different one, you might not even be aware that a wolf who is already hunting is supposed to disappear from the list.
It would just be easier for me to keep track of it if my wolf wasn't visible if it's already in a different hunting quest, to keep from mistakenly adding the same wolf multiple times.