This link shows how use a stick or HD but I dont know if you can use two directories both https://github.com/digitalLumberjack/recalbox-os/wiki/Auto-mount-of-usb-in-place-of-share-partition-(EN)

Hey there! Im just installed recalbox running away from retropie. Its amazing and very easy but I dont have select button and anyone free so I want to use a hotkey command to "insert coins". Is is possible? Thanks fellas