title: What is the effect of rewriting internal links with mod-rewrite on search engines
body: <p>Currently I'm working on a project in which i have to add multi-language functionalities to an existing website. The used link structure (URL:) is similar to: "www.sitename.com/page-alias/", this must stay the same even after the multi-language update. </p>
  
  <p><strong>URL's like this are not welcome</strong>:</p>
  
  <ul>
  <li>www.sitename.com/en/page-alias/</li>
  <li>www.sitename.com/nl/different-alias/</li>
  </ul>
  
  <p>I managed to get the job done with a .htaccess rewrites on both www. (there is an active rewrite to change without www. to with www.) and a rewrite that removes the /en/ &amp; /nl/ part. </p>
  
  <p><strong>The parts in my .htaccess file that does these changes</strong>:</p>
  
  <pre><code>#from without www. to www.
  RewriteEngine on
  RewriteCond %{HTTP_HOST} ^sitename\.com$
  RewriteRule ^(.*)$ http://www.sitename.com/$1 [R=301,L]
  
  #remove language from URL
  RewriteRule ^en/(.*)$ /$1 [R=NC,L]
  RewriteRule ^nl/(.*)$ /$1 [R=NC,L]
  </code></pre>
  
  <p>But, the CMS we use (CMS made simple) creates a link structure similar to the URL's displayed in the list below. Unfortunately their doesn't seem to be an easy way of changing the link structure made by the CMS:</p>
  
  <ul>
  <li>sitename.com/nl/page-alias/</li>
  <li>sitename.com/en/different-alias/ </li>
  </ul>
  
  <p><em>"No www." and "with language"</em></p>
  
  <p><strong>My question</strong>: </p>
  
  <p>Does the link structure created by the CMS have: </p>
  
  <ul>
  <li>a negative effect on the indexing in search engines? </li>
  <li>duplicated content? </li>
  <li>any other drawbacks / negative influences? </li>
  </ul>
  
  <p>Or does the .htaccess solve this problem? </p>
  
  <ul>
  <li>Do search engines notice that those different URL's all belong to one page and still give it the right indexation?</li>
  </ul>
  
  <p>Keep in mind that the whole website(source) gets filled with incorrect links. </p>
  
  <p>I hope you guys can help me understand / solve this.</p>