Implementing SEO programs on a website can be a time consuming affair when you first start and for webmasters their site is, well, just their site. By this I mean, the site is just one entity. This is often the first basic mistake that many webmasters make.
In reality, your site is made up of many entities. For the search engines, your site as a whole doesn’t exist – at least not when it comes to search results. Your site is made up of pages and they are the entities that search engines care about. If you use secure pages, in other words you use the https: rather that the straightforward http:, then you may need to double check on several issues – one of which could be duplicate content.
For most websites, once you have incorporated a secure area in your site, the https: usage can connect with all pages – this includes the non-secure area. In other words, if your home page is http://yoursitenamehere.com and you have a secure section, your site’s home page can also then be accessed using https://yoursitenamehere.com.
Duplicate content is not supposed to be a big issue these days. That is still debatable with some experts swearing it still has a negative effect whilst others insist it has no effect at all. Whilst I don’t believe it is a big issue now, it doesn’t hurt to insure the right pages appear in the search engine results.
The easiest way to control this is by using a nofollow into all of your secure pages. This of course means your secure content will not be indexed. For most sites, the secure section deals with payments so not having it indexed is not a problem.
If those pages have been indexed, either go to, or create, a Google Webmaster Tools account. From there you can send in a request to have unwanted pages removed from the index. From that point on your secure pages should never appear in the search results and you should never have any SEO problems related to duplicate content.