As the author of this intentional duplicate, I would argue that this is okay practice as long as it is done in moderation.*
I was asked about the topic of the question (quoting BE text in an AE paper, or vice versa) today by a fellow student. I tried to search for an answer (and I like to think I'm a decent Googler), but didn't find the English.SE post - even though it provides the best quality discussion on the matter that I could find.
The absence of the English.SE post from my search results was because I searched with a set of keywords that was wildly different from that post's title (my key words were something along the lines of,
American English text quote British English preserve spelling).
There was no organic way to integrate the Google keywords I initially searched for without significantly altering the original question. To me, tampering with the original in that way would have been the worse choice, ugly SEO possibly diluting the post's quality and making it less succinct.
In my opinion, in such a case, it is legitimate to create a "fake" question with the right keywords, with the sole intention of having it closed as a duplicate.
Also, Stack Exchange's official reason for keeping closed duplicates around is SEO - had I simply posted the question without the information that I did it intentionally, it would have simply been closed as a duplicate.
* I would oppose, for example, someone going around and creating dozens of "SEO targets" willy nilly.