title: Change Wix Merge Module Package GUID?
body: <p>When is it necessary to change the package GUID of a merge module? </p>
  
  <pre><code>&lt;Wix xmlns="http://schemas.microsoft.com/wix/2006/wi"&gt;
   &lt;Module Id="MyMergeModule" Language="1003" Version="1.0.0.0"&gt;
    &lt;Package Id="SOME_GUID" Manufacturer="Me" InstallerVersion="301" /&gt;
   &lt;/Module&gt;
  &lt;/Wix&gt;
  </code></pre>
  
  <p>Wix3 requires that the package GUID is explicitly specified for a merge module unlike for a product. My merge module will be used with an MSI that is built bi-weekly. These bi-weekly MSIs need to co-exist on the same machine as separate installations (e.g. versions 1, 2, 3, etc...) Do I need to change the package GUID of my merge module for each bi-weekly MSI build?</p>