Many e-commerce website tools now come with SEO add-ons to enable you to make them more SEO friendly but one thing there still seems to be problems with is duplicate content issues.

A number of the e-commerce packages available provide the option to produce HTML versions of the product catalogue on the site, which sound great to many companies as an extra way to promote their products, however this is a great way of duplicating content for every product on the site, so where possible avoid this or if it is pushed then the containing folder could be disallowed in the Robots file to stop Search Engines from crawling these pages and penalising the site.

In addition many e-commerce websites have a http and https site for secure payments. If the https site is crawled and indexed by Search Engines you will also suffer from Duplicate content issues as the https site may not just contain the check out and payment pages but also the rest of the site.

If you manage the SEO on an e-commerce website you can use Google's webmaster tools to stop the https site from being crawled and indexed. Once you have set up the main http site in Google webmaster tools and verified it with Google you can then add an additional site with the same URL but https at the beginning - so your main site is www.yourcompany.com and the additional site is https://www.yourcompany.com - your verification file for the www.yourcompany.com site will verify the https://www.yourcompany.com site. Using the Tools menu under the https site select remove URLs and remove the entire https site - making sure it's the https and not the main site you are removing and submit the removal request.

Doing this should ensure that the duplicate content issues on the site are removed.