Duplicated content issue?

[LauraHT]

Hi,

Moz tools tell me that I have approx. 15xx Pages with High Priority Issues [Duplicate Page Content]

going thru the details here are the majority:

• many products no longer exist and visitor redirected (404) to a same not found page.

• duplicated content with url appended with utm_source/utm_medium/utm_campaign GA tracking paras. On those page there are already canonical tags plus I've configed those parameters in Google Webmaster "URL Parameters"

how much of these warning could compromise the seo proformance or provided that there have been dealt with should I just ignore these warning?

[GPainter]

- many products no longer exist and visitor redirected (404) to a same not found page.

Rather than a 404 page give a 410, this tells search engines that page is gone and its never coming back rather than just not found, will help remove the pages from Google as well.

Google's pretty cleaver and Moz doesn't always get it right with duplicate content and canonical if you feel a lot of the pages are justified or serve the user as they are (e.g. telling them the page no longer exists) then it will be fine.

In the large scheme of things the duplicate pages are not going to do you harm but its worth keeping an eye on it and doing your best to avoid them if possible using the canonical tag etc. but if you have done all you can i wouldn't loose any sleep.

Lastly You can try Screaming Frog to help you find duplicate content if you want another look from a different tool.

Hope some of that helps. Good luck!