How Duplicate Page titles generated?
Let's take an example of an online clothing retailer - xyz.com. In Women's clothing department, we find these different products:
- Brand Name Sweater, Small, Red
- Brand Name Sweater, Small, Blue
- Brand Name Sweater, Small, Yellow
If the page titles for these product pages are automatically generated, all of them will have almost identical page titles. This will show up as a warning in your Google Webmaster tool account, or SEOmoz's crawl report, showing that there are 3 pages with duplicate page titles. They are not same, but in search engine's eyes, it is duplicate. There is no magical formula by which you can estimate if search engine will filter out your results as duplicate. There is no certain percentage either.
How to solve Duplicate Page Titles for Product pages:
There are few ways to fix this problem:
1. Start with the difference:
Rewrite the page titles so the main difference between those products are stated upfront. New page titles will look like this:
Red Band Name Sweater, Small
Blue Band Name Sweater, Small
Yellow Band Name Sweater, Small
2. Use Canonicalization:
Canonicalization is a process to pick an important page from a group of similar pages and implementing canonical tags on other pages. For example, if Red Sweaters are more important than other colors, include this line in <head> section of in all non-canonical pages:
<link rel="canonical" href="http://www.xyz.com/red-brand-name-sweater.html">
This will suggest the search engines that we prefer the red page to be indexed rather than this page.
3. Improve site architecture:
Having an individual page for each and every version of a product (red sweater, yellow sweater for small size; red sweater, yellow sweater for medium size and so on ) in itself is a bad practice. Consider re-designing your information architecture in such a way so that there is only one page for a product type. Include drop down boxes to give options to select size, color etc from the same page. JCPenney.com is an excellent example to show this in action: 
I hope this article helps you in solving one of the most common ecommerce SEO problems. Do you find this helpful? Rate this article. Do you have any other way to solve this issue, please share it with rest of us.
