Search Engines do not like duplicate content. Duplicate Content might be at two different websites or two different pages, try not to have duplicate content,
Here are some tools provided to check the duplicate contents:
The links that sometimes are seen as a set of links under the main site are Sitelinks. These Sitelinks are sometimes shown by search engines as a search results for site. The Sitelinks help users to see list of links in that site.
The figure above shows the sitelinks of photoos.net, the popular photo collection(sports and events) site from Netherlands.
Google generated sitelinks are automated and the site should be well structured to meet the Google sitelinks algorithm containing at least of three sitelinks so as to appear on search results.