Hey! Just wondering if it’s possible to have a topic show up in 2 different categories. For example, if we had a “News & Updates” category explaining how a new mobile app feature will be available soon. Would I be able to have that same topic show up in the “Mobile App” category, or would I have to rewrite the same post?
Thank you 
As far as I know, a topic/post can only exist in one category.
Topics exist in exactly one category.
Rather than duplicate the text, I would link to the announcement in a new topic in the other category. That way there is only one place to comment.
This works, if either category is viewable for the same people.
I would love to think about how topics or single posts could be shared in multiple categories.
Quote entire post and post it in a new topic. You may need to adjust title.
A case use of the full quote. 
Like what @pfaffman said. I have often used similar for discussion on announcements.
Thank you! That makes sense