ngRepeat: Dupes when posting data with angular

$http.post(url ,// Application module
var reportRequest = angular.module('reportRequest',[]);

reportRequest.controller('reportRequest', function($scope, $http) {

    // create a blank object to handle form data.
    $scope.report = {};

    // calling our submit function.
    $scope.submitForm = function() {
        // Posting data to php file    
        $http.post(url, {
            "selectPerson" : $scope.report.firstname
        }).success(function(data){
            // Stored the returned data into scope 
            $scope.people= data;
            console.log(data);
        });
    };
});

<table class="table table-hover">
<tr>
<th>First Name</th>
<th></th>
<th></th>
</tr>
<tr ng-repeat="person in people track by $index | filter:search_query">
<td><span>{{person.firstname}}</span></td>
</tr>
</table>

Copyright Notice：Content Author:「dallas」，Reproduced under the CC 4.0 BY-SA copyright license with a link to the original source and this disclaimer.
Link to original article：https://stackoverflow.com/questions/44202508/ngrepeat-dupes-when-posting-data-with-angular