title: Using duplicate parameters in a URL
body: <p>We are building an API in-house and often are passing a parameter with multiple values.</p>
  
  <p>They use: mysite.com?id=1&amp;id=2&amp;id=3</p>
  
  <p>Instead of: mysite.com?id=1,2,3</p>
  
  <p>I favor the second approach but I was curious if it was actually incorrect to do the first?</p>