In Are You A Werewolf?, the game begins with two werewolves, and each night, they kill one of the townsfolk. However, I have never seen a set of rules where it says how they decide who to kill. What if they don’t agree? Obviously, anything that makes too much noise would give them away.
The “obvious” answer is, they decide (or the GM decides for them) on the first night which one will choose first, and then alternate, but is that the way everyone plays it?
When we played it the system was pretty ad hoc : everybody closed their eyes for then night, werewolves opened theirs and then there was lots of finger pointing and head shaking, nodding or shrugging. The DM did make a point to narrate louder at night and/or to up the background music.
If they really vigorously disagreed I suppose their neighbours at the table might suss something out from all the movement and faint noises but eh. It’s not like they can use it in “court” - for one thing OOC or meta stuff like that would be frowned upon as a matter of course, for another are you really going to trust the guy who swears up and down he heard his neighbour moving ? COME ON, SHEEPLE, he’s obviously a werewolf trying to throw off the scent, I say we burn him ! :). Or it could be somebody deliberately shifting about at night to mess with people’s heads 
(who, *moi *? Why, I never ! The very idea !).
The game is as much about freeform roleplay and/or improvisational insane troll logic as it is about winning anyway. Least the way we played it.
Then again it *was *an RPG & board games retreat slash holiday camp, so 
I’ve only played online, where private communications are simple to set up.
That said, though, since the wolves know who each other are and can trust each other, it usually seems to be pretty easy for them to come to a consensus agreement.