Clojurians Log v2

Hey all, how can I duplicate an element in a vector? For example:

[{:a 1} {:b 2 :duplicate 3} {:c 3} {:d 4}] => [{:a 1} {:b 2 :duplicate 3} {:b 2 :duplicate 3} {:b 2 :duplicate 3} {:c 3} {:d 4}]

I was thinking about transform with flatten:

(->> x (transform [ALL (pred :duplicate)] #(repeat (:duplicate %) %)) flatten)

But how can I do it when the vector is in a nested structure?

{:a {:b { :x [...] }}