Most of the search engines prefer unique content on the web pages and blogs. Webmasters who want to avoid any current or future bans will do well to follow these simple guidelines in order to avoid duplicate content penalties:

Redirects

If you redesign your website, use permanent 301 redirects. Redirects are a legitimate way of routing web traffic.

Unique web pages

Each page within a website should be unique. The focus of each page on a website, even if it’s similar to the theme of another page, must contain unique and original content.

Multi-Language

If there are multiple language versions of a website, consider using a different domain for different versions; search engines do not view an article translated into a variety of foreign languages as being duplicated content — each language version is unique content in the eyes of the search engine.

Unique Meta Tags

Each web page should contain unique meta tags.

Robots.txt

If you do have intentional duplicate content on your website, be sure to have a “robots.txt” file for your site to prevent the search engines from indexing the areas with duplicated content (or any areas of the website that you wish to remain private, for that matter).

Affiliate Twist

If you are promoting products or services using an affiliate program, use unique and distinctive product descriptions and web copy. If you simply use the same descriptions provided by the product owner or service provider, it’s very likely that your copy could be viewed as duplicated content.

Copyright notice

Include a copyright notice on your website.

Enforce copyright

If you discover that another website is scraping your unique web content and replicating it, enforce your copyright! Use CopyScape, or use their “copy sentry” service to receive notification of any infractions. If you discover a copyright violation, contact the website and politely request appropriate changes.

If the changes are not made in a reasonable and satisfactory amount of time, contact the ISP (web host) of the infringing site, and file a DMCA complaint with Google.

Avoid Identical Content

Do everything you can to avoid serving a web page that contains content identical or closely related to another page. If for some reason you have two pages that contain identical content, use a robots.txt to block the search engines from spidering one version of the page.

Sign for Duplicate Content

Other Tools:

While it may still be debatable whether all the major search engines currently employ a duplicate content penalty, all have made it abundantly clear that they do not have any desire to provide search results that rehash the same content over and over. Actively avoid any potential penalties by taking a proactive approach to building unique content.