Using Ember 1.4, EmberData beta 7 with default REST adapter. I don't have a JSBIN because problem only shows when there's a success reply from the server. Here's the scenario:

1. create 2 routes, and transition to the 1st route.
2. create a record: amd = store.createRecord ('myModel', myRecord);
3. save the newly created record: md.save();
   note - server must return a success for problem to show. My server returned {status, 204}
4. now transition to route 2 via link-to or something else, then hit the browser's back key to go
   back to route 1.
5. when the 'back' button is pressed, Ember makes a GET request to the server.
   (why does Ember send a GET message when it already has it in the identity map?)
   Server replies with one instance of the saved record. Ember displays two instances of
   the saved record. Ember inspector also shows two instances.
6. Now if the browser refresh button is pressed, Ember sends a GET to the server. Server replies
   with 1 record, and everything looks right again.