title: Why signtool.exe don't support /as option while dual sign SHA2 and SHA1
body: <p>I got error about /as option when dual sign SHA2 and SHA1</p>
  
  <pre><code>signtool sign /v /n "name" /sha1 "sha1 hash" /t http://timestamp.verisign.com/scripts/timstamp.dll my.exe
  signtool sign /v /n "name" /sha1 "sha1 hash for sha256" /as /fd sha256 /tr http://timestamp.geotrust.com/tsa /td sha256 my.exe
  </code></pre>
  
  <blockquote>
    <p>SignTool Error: Invalid option: /as</p>
  </blockquote>
  
  <p>I guess if my signtool.exe version is not support /as option? I used signtool.exe version is 6.1.7600.16385 BTY, i can sign SHA2 successfully without /as option.</p>