Many sites feature a way to print a page of your site in a printer friendly view, by removing many of the ads, removing a lot of the navigation and so on. The issue with this, in some cases, is that webmasters creating a new URL with the same content, causing a duplicate content issue on the SEO front.
The best solution is to use a printer friendly CSS template. This will ensure that the URL is the same, no matter what view is given to the user or search engine. If you cannot create a CSS template for printer friendly versions of the page, then the next best thing to do is exclude those printer friendly URLs (i.e. the duplicate URLs) with a robots.txt file.
One person asked in a Google Webmaster Help thread, can they use the newish rel=canonical link element to redirect search engines to the main URL, so they pass the link equity? Googler, JohnMu, said you shouldn't. He said, "I don't think using the rel=canonical link element would be that valid here, since the two pages do look pretty differently (they're not really interchangeable canonicals)."
Let me show you a real life example of what we did on RustyBrick.com, my real business (outside of this blogging stuff, which is just a hobby for me).
On Thursday, we launched a redesign for the RustyBrick site, a redesign and technology upgrade nine-years in the making. Part of that was to fix this issue.
- Created a print CSS template
- 301 redirected the ?print_page=1 to the parent URLs
In addition to that, we created a neat mobile template, which uses the useragent to change the CSS (not the URL) when you access the site on most mobile devices. And our print pages are also using the same URL and look pretty good.
Here are pictures of the same URL on a desktop web browser, on an iPhone and as a print friendly page:
There are some things we still need to clean up with this design and our templates, but for the most part, I am happy with the look, feel and search engine friendliness of the new site.
Forum discussion at Google Webmaster Help.
Oh, and to comment on the new design, go to my blog post at the RustyBrick Blog and comment there.