title: Duplicate symbols (two projects in a workspace use the same code)
body: <p><code>A</code> is a module project. There are some test targets and the relevant reusable code is compiled in a separate (static library) target. <code>A</code> uses the third party Lumberjack logging library. The Lumberjack code was simply dropped into the project.</p>
  
  <p><code>B</code> is a different module project, but otherwise it has the same properties as <code>A</code>.</p>
  
  <p><code>C</code> is the main project. It depends on <code>A</code> and <code>B</code>. It links the libraries of <code>A</code> and <code>B</code>.</p>
  
  <p>Compiling <code>C</code> will result in duplicate Lumberjack symbols. </p>
  
  <p>How can I have multiple separate module projects so that...</p>
  
  <ol>
  <li>they don't know of each other,</li>
  <li>use the same third party code,</li>
  <li>can be compiled and tested on their own,</li>
  <li>included in a main project without duplicate issues?</li>
  </ol>