No pair of Sharkes broke 50% overlap (which is why two of the colors in the key don’t show up). Sharkes mostly had at least one book in common with most of the other Sharkes’ shortlists. The one person who really stands out is Vajra, but that’s more or less by construction, since it appears that he deliberately picked books that hadn’t been chosen by anyone else. (The Core of the Sun was his one exception.) Other than that, the one Sharke who is a bit unusual is Nick, who had 50% overlap with three Sharkes and zero overlap with three others.
I also note that out of the total of 86 Clarke-eligible books, the 9 Sharkes collectively picked 27, so just about 30%. 13 out of those 27 came from non-genre publishers (I think). Out of all the Sharke lists, there was 1 book that appeared on 5 shortlists (The Underground Railroad), 3 that appeared on 4 (The Core of the Sun, A Field Guide to Reality, Central Station), 3 that appeared on 3 (The Power, The Gradual, The Many Selves of Katherine North), and 8 that appeared on 2 (The Destructives, Fair Rebel, Infinite Ground, Good Morning, Midnight, The Fifth Season, Occupy Me, Azanian Bridges, The Arrival of Missives). Thus a little less than half the total (12/27) were picked only by a single Sharke.
It should certainly make for some interesting reading! (Even as it dings my bank balance – I already have three books from Sharke shortlists on order).