Say I've written two articles: one on interesting plot twists and another on how to write a plot twist. If the "interesting plot twist" post already ranks quite highly for the keyword 'how to write a plot twist', does it make it less likely that the other post will get a high ranking for that keyword too. Does Google prefer a diversity of domains in its SERPs, meaning that your own posts can block your more relevant posts from rising to the top?
As has been stated above - this question is actually about strategies for writing about topics.
Yes, keep writing, but.... in a structured way.
Revisit. No web page is fixed in concrete.
Review the existing page. Does it provide an 'overview' of the topic or go into too much detail on too many aspects? Look for paragraphs which you could fill-out and discuss in more detail. These can become second, third, fourth pages. Focus on the key phrase of each page, if it helps you to write a tightly focussed page of copy.
By constructing topics this way and so writing in a structured way, it leads naturally to pyramids of pages around a single topic. Pyramids of pages are good. They completely play into the semantics thing, create an 'expertise' and best of all - visitors to your website get a great coherent experience which they can explore as much or as little as they like.
Of course, @closetnoc's philosophy of 'just write' is a good one. Just add 'and review' to the end of the statement. Just write and review.
Repeated content (with minor tweaks) is adding little value for the visitor...