I suppose that this is edging dangerously close to starting a semantic argument, but I'd personally argue that ad-hoc polymorphism is a distinct concept from duck typing that just happens to have a lot of overlap in its use cases. One key distinction is that Clojure multimethods need to be explicitly declared somewhere, whereas duck typing is 100% implicit.

And in everyday Clojure usage the equivalent of Python attribute access is key access on maps, which is even more directly duck typed.