title: Generate unique random numbers in Dart
body: <p>How can I generate two different random numbers in dart? </p>
  
  <p>I have generated two random numbers using code below. </p>
  
  <pre><code>int rand1 = Random().nextInt(16);
  int rand2 = Random().nextInt(16);
  </code></pre>
  
  <pre><code>if(rand1 == rand2)
    // generate new random 
  </code></pre>
  
  <p>How do I generate new random numbers until <code>rand1 != rand2</code>?</p>