Ok, I feel like I'm rambling on about this but here goes.
If a wolf is up for lynch and they have the duke ability, they will 100% use the ability to try and save themselves. At this stage of the game, the odds are about 50/50 that they pick another duke and each die.
If a (unroled) villager duke is up for lynch, and they try to save themselves, they also have the same odds, however, the odds of pulling a wolf are really bad at this point. So unless they have a strong suspicion of who the wolves might be, it would be better for the village if that vanilla duke just let themselves get lynched.
So what I am trying to convey, is that while in the past, the vanilla villagers have tried to save themselves at all costs from a lynch, in this particular game, it may be better for the entire village if that person does not use their ability, at least this early in the game.
If the dukes start eliminating themselves, the wolf duke(s) will have more escape routes from lynching later on in the game.