Namespaced keywords can cause multiple attributes on an element

[SVMBrown]

I was investigating handling of namespaced keywords in hiccup and reagent and stumbled across the following behaviour:

(html [:div {::id "abc" :id "123" :my.ns/id "xyz"}])
;;=> "<div id=\"123\" id=\"abc\" id=\"xyz\"></div>"

Not entirely sure what behaviour should be, but for my use case I was hoping that all namespaced keywords would not be included in the final rendering. Figured I would mention this edge case in case it is relevant.