title: Sending push notification from different servers
body: <p>We have an app. App can register to <strong>different servers</strong>: Server1 and Server2.</p>
  
  <p>Now, Server1 and Server2 wants to send push notifications to an app <strong>independently</strong>. How to solve it using GCM?</p>
  
  <p>I don't know how to implement in the sense of <code>SenderID</code>, <code>registration token</code>. Can an app has <strong>one</strong> <code>SenderID</code> for every app server? Should I has a one SenderID and generates different registration token for every app server?</p>