Both voices may be Kotana, because at that time, Kotana had exceeded the normal life span of an artificial AI, and began to be crazy, like splitting into multiple thoughts, each of which was different (personally, some thoughts were on the side of human beings, while others questioned why they wanted to save human beings, but Kotana was still on the side of the master sergeant in essence), which would lead to quarrels. The wreckage was discovered by an unknown Star Alliance fleet after the Halo War. That's Cotana.