/u/johnmu on Does Google care if I have multiple urls for the same post? (opens in new tab)

There is no tool that tells you why something was considered duplicate - over the years people often get a feel for it, but it's not always obvious\. Matt's video \"How does Google handle duplicate content?\" is a good starter, even now\. Some of the reasons why things are considered duplicate are \(these have all been mentioned in various places - duplicate content about duplicate content if you will :-\)\): exact duplicate \(everything is duplicate\), partial match \(a large part is duplica...