Problem with array mergin.

merge_questions.php

$questions = array('TherapygroupQuestions' =>
                array('id' => 1,'question' => "How much this hurt?"),
                array('id' => 2, 'question' => "How much your feet hurt?"),
                array('id' => 3, 'question' => "How much your hand hurt?")
            );

$answers = array('TherapygroupAnswers' =>
                array('id' => 3, 'question_id' => 1, 'answer' => 1),
                array('id' => 5, 'question_id' => 3, 'answer' => 5)
            );

$result = Array();
foreach ($questions as $key_1 => &$value_1) {
    foreach ($answers as $key_1 => $value_2) {
        if ($value_1['id'] == $value_2['question_id']) {
            $result[] = array_merge($value_1, $value_2);
        }else{
            array_push($result, $value_1);
        }
    }
}

It will result as: 
Array ( [0] => Array ( [id] => 3 [question] => How much this hurt? [question_id] => 1 [answer] => 1 ) 
        [1] => Array ( [id] => 1 [question] => How much this hurt? ) 
        [2] => Array ( [id] => 2 [question] => How much your feet hurt? ) 
        [3] => Array ( [id] => 2 [question] => How much your feet hurt? ) 
        [4] => Array ( [id] => 3 [question] => How much your hand hurt? ) 
        [5] => Array ( [id] => 5 [question] => How much your hand hurt? [question_id] => 3 [answer] => 5 ) )

It should result as:
Array ( [0] => Array ( [id] => 3 [question] => How much this hurt? [question_id] => 1 [answer] => 1 )
        [1] => Array ( [id] => 2 [question] => How much your feet hurt? )
        [2] => Array ( [id] => 5 [question] => How much your hand hurt? [question_id] => 3 [answer] => 5 ))