title: Does npm install package twice?
body: <p>I run <code>npm install</code> to install my dependencies.</p>
  
  <p>At the first time, some package install failed.</p>
  
  <p>I ran <code>npm install</code> again.</p>
  
  <p>Will <code>npm</code> reinstall every dependency again or just the package not be installed?</p>