I think I get the question, but it is awkwardly worded. In my opinion, the "second visitor" would be the giant rabbit that emerges in Lennie's sight as he is hiding from the lynch mob at the hiding place that he and George established at the start of the narrative. The rabbit is almost tormenting Lennie about how Lennie will be beaten and abandoned. This is reminiscent of how Crooks tormented Lennie in chapter 4 about George leaving him and Lennie being all alone. At this moment, the death of the rabbits and the abandonment issue all come together in Lennie's vision and it is horrifying for him, as it represents a world spinning out of control. It is a moment where much of Lennie's experiences unify together. It is also significant because George's arrival results in the rabbit disappearing. Yet, all of these thoughts remain in his mind, only to be replaced with one last hopeful vision of the farm and the dream it represents. In the end, the second visitor reminds Lennie of the discussion with Crooks about loneliness and abandonment and the pain experienced with such emotions.