100% I have built similar behavior in my [0] encrypted storage app for iOS. User creates a "duress vault" which is an ordinary vault that user can store any data they want (usually something very inconspicuous). If this vault is opened, it will wipe out all the other vaults silently without actually showing any sign of doing so and still preserving the duress vault's data. Even if snapshot of files is made, the index and keys are gone and can't be recovered.