Firstly we need to know about the word duplicate content. People with no SEO experience use this phrase all the time. Most people have not read Google guidelines on duplicate content. Duplicate content means appearance of a content more than one place. It can be difficult for search engines to decide which version is more relevant to the given search query. Here you can find informative data about The Myth Of The Duplicate Content Penalty.

Non Original Content on Your Site Will Hurt Your Rankings across Your Domain

If the content that you are posting on your site is a duplicate content then it may hurt your rankings. Google is very sharp in finding those sites which are posting duplicate content articles. Many sites, including some if the most popular blogs on internet, frequently use articles that first appears somewhere else. They do not expect this content to rank because this is the duplicate content. If you post original and unique content on your site then Google can easily rank your site. If you want to know about duplicate content then you can find information from this topic The Myth Of The Duplicate Content Penalty. 

Scrapers Will Hurt Your Site

There are some bloggers who carefully watches Google Webmaster Tools. When the scraper site copies their content they quickly reject any links to their site. You should report scrapers that outrank your site. Here you can find informative data about The Myth Of The Duplicate Content Penalty. On very rare occasions, Google gets confused and the copied version of your content is outranking your original.

Republishing Your Guest Posts on Your Own Site Will Hurt Your Site

I have also done a lot of guest postings. Its unusual to republish these guest posts on my own site,. The first and the foremost rule is that the content must be original and free of plagiarism. Canonical is a fancy word that means official version. If you want to republish an article that first appeared elsewhere then you can use canonical tags to tell search engine where the original version appeared. Here you can find information about The Myth Of The Duplicate Content Penalty. If the content on your site is original then Google may not take your site as spam site.