Identify similar contents in encrypted data? Is it possible to compare two ciphertexts (two different encryption algorithms are used to create ciphertexts) to identify redundancy?
Not if the encryption algorithms work. And not even if it's the same encryption algorithm. This is a consequence of one of the properties required for an encryption algorithm to be considered secure: ciphertext indistinguishability under chosen ciphertext attack. If an adversary can send ciphertext 1 for decryption, and from that learns something about ciphertext 2 (such as a similarity in their corresponding plaintext), then this property is violated.