I have an Orico 10 port USB3.0 powered hub that I bought a while back, and have recently come into possession of a pair of RPI2 Model Bs. I was wondering how the "power distribution" on hubs worked; and if I could power my Pis via the ports on the hub, or if the power output would fry my them. The power adapter for the hub has a 110-240VAC input at 50-60 Hz and outputs 12v at 4 amps to the hub itself.
Most likely yes
The product spec reads:
The ten port model features a 4 Ampere power supply, while the four and seven port models come with a 2.5 Ampere model. This allows up 900mA per port for several, but not all ports at the same time. Typically users have a mix of 900mA, 500mA, 300mA, and self powered devices attached to a hub.
So unless there are more really power hungry peripheral devices connected to the other 8 ports it should be possible to drive two Pi.
The FAQ at raspberrypi.org states a "recommended PSU current capacity" of 1.8 A for the Pi2B. This includes 1.2A to downstream USB peripherals connected to the Pi. So if no power hungry devices are connected to the USB ports of the Pi the 900 mA should suffice to power each.
Because this power consumption statistics have been brought up in another question. Their measurements suggest a current of 800-1100 mA (~4W) for the Pi2B under full load. Well that should make one at least think twice. As always this boils down to how reliably the hub limits the current on its ports (many don't do a good job in sticking to the spec).