Found this in the wild, if we're all talking 4.2 then....
"To support multi-user capabilities this will be the norm... for each user, there will be a sequentially numbered folder in /data/media (/data/media/0, /data/media/1)...
And for each user, within Android, this will be symlinked to /sdcard & /storage/sdcard0... for user 1, /sdcard = /storage/sdcard0 = /data/media/0... for user 2, /sdcard = /storage/sdcard0 = /data/media/1...
These are emulated storage points... /data/media/0 = /storage/emulated/0, /data/media/1 = /storage/emulated/1
Without root access, each user will just see /sdcard/ and will not be able to access the other emulated storage points...
In the recovery mode, however, /sdcard is mapped to /data/media which is why you need to navigate to the "0" folder to see your files"!