title: Using LINQ to find duplicates across multiple properties
body: <p>Given a class with the following definition:</p>
  
  <pre><code>public class MyTestClass
  {
      public int ValueA { get; set; }
      public int ValueB { get; set; }
  }
  </code></pre>
  
  <p>How can duplicate values be found in a MyTestClass[] array?</p>
  
  <p>For example, </p>
  
  <pre><code>MyTestClass[] items = new MyTestClass[3];
  items[0] = new MyTestClass { ValueA = 1, ValueB = 1 };
  items[1] = new MyTestClass { ValueA = 0, ValueB = 1 };
  items[2] = new MyTestClass { ValueA = 1, ValueB = 1 };
  </code></pre>
  
  <p>Contains a duplicate as there are two MyTestClass objects where ValueA <strong>and</strong> ValueB both = 1</p>