I did some quick research and found some precedent:
- example precedent #1 says "Yes, it is perfectly acceptable to mark an older post as a duplicate of a newer one. The duplicate banner is a road sign for future readers; it should point to the best answer(s) available, be they under the older or newer version of the question."
- example precedent #2 says "If a newer post covers a subject better, has more information and / or covers the subject in a more general scope, then it does not matter which post is the older one. We want to lead people to the best, highest quality information."
IMO the first one Where is the Ubuntu console on Windows10?Where is the Ubuntu console on Windows10? is better and so the second older one should be marked as a duplicate.