There is this question:
Which is really a duplicate of this question:
However, the latter question is closed as "not constructive".
That said, should the former question be closed under "exact duplicate", or as "not constructive"?
The good thing about closing as an "exact duplicate" is that the question is linked to a "root" question, if due to some reason (reopen votes, culture shift, etc) the status of the root question is changed, that status automatically applies to all questions that are marked as duplicates.
However, in closing as an "exact duplicate", you run the risk that people will not click through to the question duplicated. If they only see "exact duplicate" and do not click through, then there is the danger that they will think that type of question is acceptable for the site, which is in fact, not the case. The "signpost" doesn't exist to help educate users what is and isn't accepted practice on the site
The pro and con for closing as the same reason as the duplicated question are the inverse of the pro and con for closing as "exact duplicate" mentioned above.