What is the folder called emulated on Android 4.3? topic

After updating my Xperia M to Android 4.3 Jelly Bean i noticed a new folder called emulated and when i opened it. there are two folders inside called 0 and legacy,I opened 0 and legacy and i also noticed that 0 contains the files from sdcard0 and the folder called legacy contains the files from sdcard1
Can anybody please explain what is it And what's the purpose of that emulated folder
Thanks.

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