title: QR Code - is uniqueness guaranteed for unique inputs
body: <p>I want to generate QR codes to pass a unique alpha-numeric code to a site. The QR will be generated from  a string like:</p>
  
  <pre><code>https://example.com/ABCD1234
  </code></pre>
  
  <p>The ABCD1234 is the unique code and there will be ~100 million of them. Can I be sure no two QR codes will be the same, and be read to 100% accuracy?</p>
  
  <p>Anything to watch out for standards wise?</p>