Programmer Humor

If you set it up correctly, this is essentially what it does. You have a disc that is, say, 1tb. It's encrypted, so without a key, it's just a bunch of random noise. 2 keys decrypt different vaults, but they each have access to the full space. The files with the proper key get revealed, but the rest just looks like noise still, no way to tell if it's empty space or if it's a bunch of files.

This does have an interesting effect. Since both drives share the same space, you can overfill one, and it'll start overwriting data from the second. Say you have a 1tb drive, and 2 vaults with 400gb spent. If you then go try to write like, 300gb of data to one vault, it'll allow you to do so, by overwriting 200gb of what the drive thinks is empty space, but is actually encrypted by another key.

It's been a while since I've messed with this tech, and I'm mostly a layman, but this should be a fairly accurate depiction of what's actually happening.