Well they both get to train together and peak at the same time. There's that advantage I suppose.
Also Rufus can't possibly be giving them both all the attention they need if they fight at the same time.. So who knows.
I don't think Pettis brother losing had anything to do with how he fought.
We've seen it 3 times in the UFC now, he has a problem with wrestlers. Granted he's beaten a few great ones in spectacular fashion. I think it's pretty clear Sergio isn't going to reach his brothers success at all.. who knows though, people said the same thing about Nate.