The NXM Quake (Quantum Augmented Key Encapsulation) solution combines both a classical and a quantum key encapsulation algorithm (for example, NTRU) for extra security in public key encryption. The concern is that classical encryption alone may already be vulnerable to a Harvest Now, Decrypt Later attack and that a quantum resistant algorithm alone may still have a latent weakness that hasn’t yet been discovered. The expectation is that any remaining weaknesses in the proposed quantum resistant algorithms will be found after the NIST Post-Quantum Cryptography selection program has completed, but this is not expected to occur for a few years. So combining the two together provides extra security. For more details, you can view NXM’s news release announcing Quake here and a video they created about it here.