Deduplication: Encrypting the SHA-256 hash of a file chunk
Information leakage in systems that do data deduplication typically involves timing hints that the data is already stored and related leverage of that information.  See the comments in https://security.stackexchange.com/questions/7142/online-backup-how-could-encryption-and-de-duplication-be-compatible/7146#7146 for insights there. Suggest you consider your attacker's profile and see of any of those issues apply as a confidentiality threat.

Efficient deduplication needs to maximize the capture of identical data and thus is typically done at the file level or some subset that will always produce the same chunks in the same file.  If your chunk boundaries plan addresses that you are good otherwise consider it.

Finally, encrypting a hash with a method that always produces the same output would appear to add very little protection if any.  The hash is by definition not reversible so the only potential value is in protecting against someone who can recreate the hash and wants to know if they are correct about the guessed plain text or binary.  That attack assumes the attacker can see the resulting hash.  If that is the case then seeing the predictably encrypted result adds very little to the attackers task as he only needs to see that the data is not moved to storage but rather already exists in the system (see first point about information leakage).