Well, two <h1> headings isn’t that big question actually. It is really old SEO meme, that hasn’t been an issue long time now. Google etc. will use the first one or what ever they think is the most suitable.
We can discuss if two main headers is the most smart move contwnt wise, but when a platfprm will use different style for topic name and headers in posts it doesn’t really matter.
Still it is more suitable to use ##/<h2> in posts. But because it doesn’t play any actual role, my opinion is it is better that users use some headers that avoid those because they are afraid of using ”wrong” headers 