The wisdom skill is individual, it's not shared. So you can end up with one character having more experience than the other.
Now, I'm not quite sure how it works, but all I know is that it's not worth getting at all. If you spend a few skill points on it, you might end up with 1 or 2 extra levels at the end of the game. There's better ways to spend your precious skillpoints.
Tovi 