title: Two enums have some elements in common, why does this produce an error?
body: <p>I have two enums in my code:</p>
  
  <pre><code>enum Month {January, February, March, April, May, June, July,
          August, September, October, November, December};
  enum ShortMonth {Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec};
  </code></pre>
  
  <p><code>May</code> is a common element in both enums, so the compiler says:</p>
  
  <blockquote>
    <p><em>Redeclaration of enumerator '<code>May</code>'</em>.</p>
  </blockquote>
  
  <p>Why does it say so? And how can I circumvent this?</p>