You can clone with
"Return the new people are only in the new-list but not in the current-list.
Both lists are lists of maps where they have at least :first_name and :last_name keys.
(let [existing (set (remove #(nil? (second %)) (map (juxt :first_name :last_name) current-list)))]
(remove #(existing ((juxt :first_name :last_name) %)) new-list)))