title: Magento custom controller action is called twice
body: <p>I added a ajax add to cart to the rwd theme, and the action controller is called twice for every http request. Any help with solving the problem or debugging is welcome, I already lost 2 weeks on this. This all works on our development environment, but acts weird on staging. The dev environment is hosted locally on MAMP, staging is hosted on OVH shared hosting.</p>
  
  <p>edit2: removed irrelevant info</p>