Both stickmount and USB otg helper will allow you to do this. I have tested with es file explorer, astro, and filepwn and both drives are visible. With stickmount they show up under /sdcard/USBstorage/. With USB otg helper they are found in storage/usbotgdrives/.
When you install games/apps from discover only one of the drives will show up. After trying a few different hubs it seems like every hub has an order it reads the USB ports. The first HD or flashdrive it finds reading in that order is the one that shows up here.