I thought that was the entire point of the hidden volume... that from outside you can't tell there is a hidden volume? And that from inside the fail-safe, you still can't tell there's a hidden volume? I may simply be mistaken.
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Uh, I think you're missing the point of how the plausible deinability works. The point is that under duress you can acknowledge that it's a TrueCrypt volume, and open it up without at all exposing the hidden volume inside. It's like having a treasure chest with a false bottom where you store your good. The fact that it can't differentiate the location of hidden volumes is... paramount.
A "hidden volume" does not mean a truecrypt volume disguised to look like a normal windows file which is what this program looks for...