在使用 ng-repeat 的时候，遇到如上问题，解决办法
http://www.anujgakhar.com/2013/06/15/duplicates-in-a-repeater-are-not-allowed-in-angularjs/
ng-repeat = "item in items track by $index"
[ISSUE]Error: [ngRepeat:dupes] Duplicates in a repeater are not allowed.
原文：http://www.cnblogs.com/shadow21/p/4235192.html