title: localhost is therefore not allowed access
body: <p>To solve CORS issue, I wrote there</p>
  
  <pre><code>header('Access-Control-Allow-Origin: *');
  header('Access-Control-Allow-Methods: GET, POST');
  header("Access-Control-Allow-Headers: X-Requested-With"); 
  </code></pre>
  
  <p>in my server site </p>
  
  <p>but during my development I'm seeing this error </p>
  
  <pre><code>The 'Access-Control-Allow-Origin' header contains multiple values '*, *', but only one is allowed. Origin 'http://localhost' is therefore not allowed access.
  </code></pre>
  
  <p>I thought allow-origin: * will solve everything? But why it says header contain multiple values?</p>