You can use the setSiteCollapsingEnabled(boolean value) method to specify whether the top results contain more than two results from the same website or data source.
For example, if a particular query returned 100 results from http://www.ibm.com and site collapsing was enabled, the ResultSet object contains only two of those results in the top results. The other results from that site appear only after results from other sites are listed.
To retrieve more results from that same site, use the samegroupas:result URL query syntax or re-issue the same query with the site http://www.ibm.com added to the query string. See Query syntax for more information.