Each person holds half of the bar. You can also turn around together and get back onto the board. This can also be a great way to teach someone a swing - let them swing side-by-side with a more accomplished flyer and they learn the leg movements by copying!
You can find out more about this trick in my books:
IMAGE CREDIT: Thanks to Emerald City Trapeze Arts. Flyers are Lynn, Andrea, Sarah and Ethan. Thanks to David Treadwell for the photo.