The way I broadcast on two sites at the same time is by using two different devices. I broadcast one through my laptop and another site using a mobile phone with a small selfie tripod. It is not the perfect situation, but for me much easier than trying to figure out OBS or other related software. The trick is being careful not to place the laptop and phone in spots where they end up showing up in the background of each broadcast. It is a little hard because you have to pay attention to differs chats at the same time.