So we all know what Google says about duplicate content - that it is not a Google penalty. Of course, you do not want to have duplicate content across your site, because it can confuse Google in what should rank first.
That being said, John Mueller from Google posted on Google+ asking, how do webmasters and SEOs find duplicate content issues.
I'm curious -- there are lots of suggestions on what to do afterwards, but how do you notice that a site has a "duplicate content problem"?
(leaving aside whether or not these are critical, etc -- I'd just like to find out more about how people stumble across / recognize these issues.)
To me, that shows a sign that Google is looking to add something to the Google Search Console to help webmasters proactively identify and then resolve duplicate content issues. Of course, the Google Search Console already has the HTML Improvements area that shows some of this.
But Google wants to know about other ways SEOs and Webmasters find these issues.
So chime in, who knows, it might lead to a better or new tool within the Google Search Console.
Forum discussion at Google+.