I want to take them at their word...but it's more up to Google, isn't it? And doesn't Google still rely (in part) on the canonical meta tag to resolve duplicates? Currently, the posted Medium post has this:
<link rel="canonical" href="https://medium.com/engineering-at-ifttt/data-infrastructure-at-ifttt-35414841f9b5">
It would be relatively easy for Medium to appropriately set that tag -- I mean, if "original URL" is captured somewhere in the API, or in the Medium post-create-admin interface (I don't know, I haven't logged into my own Medium for awhile)...that would explicitly resolve the ambiguity, though at an obvious cost to their own SEO.