I was reviewing questions from new users.

So, I got well known, one time Stack Exchange network hot question about broken RJ-45 plug presented to me as question from new user. My instant though was - this is duplicate! I even was surprised that this new person put exactly same picture in his question. Without even thinking I pressed flag to attract moderator's attention.

Well, after that a banner appeared informing me that I need to stop and listen and that my review was inappropriate.

I know it was high quality question and I would accept it otherwise if it would not be a duplicate.

What is correct way of handling these questions?

Should this testing behavior be fixed and allow reviewer to mark it as duplicate and pass the test?