angular/angular.js — pull request #4472 by mmieszek (2013-10-16 21:19:56+00:00)
Title: Adding the same expression twice causes ng-repeater duplicate key error

This can be resolved by adding: "track by $index" to ng-repeater. This way items are keyed by their position. For reference see:
http://docs.angularjs.org/error/ngRepeat:dupes