Why? They just wanted to chew on stuff and play follow the leader. And babysitters get paid to do this. What a job!
Moral of the story: People handle multiples all the time. If you are in a situation where you have to watch multiple kids, ease into it and be thankful you get to give them back at some point. (Eva's so cool I'd keep her, but her mom kinda likes her and I'm not ready to try to put them both to bed at once, or down for naps, sheesh!)