title: Only Single GitLab CI Runner Building
body: <p>I recently installed GitLab and am attempting to use GitLab CI. I successfully enabled GitLab CI in my GitLab Server and successfully installed a CI Runner (on Windows, if this is relevant). I enabled a project for the Windows CI Runner and when I commit to the repository the runner is executed and I can see the builds.</p>
  
  <p>I installed a second CI Runner (on Debian) following the documentation. I can see the Debian CI Runner is registered, along with the Windows CI Runner. The Debian CI Runner has the same project assigned to it. However, when I commit to the repository only the Windows CI Runner is executed, the Debian CI Runner is not attempting to build.</p>
  
  <p>What mistake have I made or what additional configuration is there to enable this? I have already tried re-registering the Debian CI Runner with no success.</p>
  
  <hr>
  
  <p><strong>Update 1:</strong> The Debian CI Runner is now executing but the Windows CI Runner is not. It seems to select only a single runner.</p>
  
  <p><strong>Update 2:</strong> Upgraded to 'GitLab CI 7.14.1 2dee1b3' but same behaviour persists.</p>
  
  <p><strong>Update 3:</strong> Added a third runner on a Scientific Linux machine. It is registered and assigned the project but only a single runner executes (currently the Debian CI Runner).</p>
  
  <hr>
  
  <p><strike>GitLab CI 7.12.0 e96755c</strike></p>