Canonical URL Tag: No Mad Rush to Implement
Recently the big three search engines teamed up and agreed on a format to help webmasters reduce duplicate content and its related disadvantages for their websites, being referred to in SEO circles as a “canonicalization tag”. Technically it’s not a tag but a value being applied to the rel attribute of the link element; if you want the gory details check the above link.
Many a CMS including Wordpress, Drupal and Magento have been known to create duplicate URLs and modules were quickly made available to implement the new tag in these systems. The good however news is that there’s no rush to patch just yet - Google most likely handles your duplicate content issues just fine already.
In this interview with Adam Lasnik of Google, Adam discusses this exact issue and states that:
[T]he happy news here is that in the vast majority of cases I have seen, we do the right thing. Our Googlebot looks at the page and if it sees a page that is pretty much identical to something it has already seen, it will automatically make a determination regarding which page makes more sense, and it will run with this URL for that given page.
And what’s more, he adds:
When we canonicalize stuff on our end, we also combine PageRank. So, if we see that people are linking to the exact same resource in three different ways, again thankfully in the majority of cases that I have seen, we are able to not only know that's the same page, we are also able to take the different links, the different URLs that are linking there, and combine that PageRank so that it gets the total PageRank from those links, and it's not separated out.
“In the majority of cases” would surely cover standard installations of the most used CMS systems out there. So, relax. You don’t need to beta-test these new modules on your production sites in order to immediately stem the leaking PageRank flow. Yes - in due course it's worth installing modules which automatically implement the “canonical tag” where relevant on production Wordpress, Drupal and Magento sites. It might help and it certainly won't hurt. But there's no rush. If you wait a bit, the modules will also get a bit of testing and stabilise before you go and whack them on production sites.
Adam sums it up pretty well with one last statement…
[I]t's best if they [webmasters] can make the changes on their end to avoid greater hassles or avoid what is at least a slight risk of some problems. But, if they are unable to make those changes, I would not spend a lot of sleepless nights worrying.