title: C# Dictionary get all keys with same value
body: <p>I have a Dictionary with Keys and Values. Is it possible to get all Key who has the same Value? </p>
  
  <p>Example <strong>1=456894, 2=548962, 3=548962, 4=654876</strong> and then get the Key 2 and 3 because it has the same value.</p>
  
  <p><code>Dictionary&lt;int, int&gt; doublechek = new Dictionary&lt;int, int&gt;();</code></p>