Two bathrooms, one exhaust vent?

I have 2 bathrooms next to each other. When the house was built, they put an exhaust fan in one bathroom but not in the other. I am wondering if there is a way to run exhaust fans from both bathroom out the same vent without venting to the other bathroom. I'm trying to avoid cutting a hole in the roof right next to the other exhaust vent, but I am not certain that this is possible.

Thanks
Nettak