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Property http://www.example.com is receiving data from redundant hostnames. Consider setting up a 301 redirect on your website, or make a search and replace filter that strips "www." from hostnames. Examples of redundant hostnames: example.com, www.example.com.
I haven't gotten the message you're asking about
I'm sure you've had a domain-name-canonicalization redirect in place for years.
Does this mean G### is getting to work figuring out which things are true Duplicate Content and which are simply the same page under different URLs? Hurrah, if so.
(No fun for google, anyway. I suspect Bing kinda enjoys it.)