数组奇怪地改变而不操纵它

我面临一个非常奇怪的行为。我有$answer_styles数组与一些数据，我需要操作:

foreach($answer_styles as $id => &$answer_style){
    $answer_style['id'] = $id;
    $answer_style_names[$id] = $answer_style['name'];
}
array_multisort($answer_style_names, SORT_ASC, SORT_STRING, $answer_styles);

，然后保存到另一个变量，以后使用:$stats['answer_styles'] = $answer_styles;

现在，我需要使用foreach循环进入原始数组。我已经这样做了:

debug($stats['answer_styles']);
foreach($answer_styles as $answer_style){
    debug($stats['answer_styles']);
        ...

问题是第一次调试显示了它应该显示的数据，但第二次调试显示了由第一个覆盖的最后一条记录(因此，从1,2,3,4开始，它现在显示1,2,3,1)。为什么会发生这种情况，因为我不操纵$stats数组，但$answer_styles一个?

编辑

这分别是第一次调试和第二次调试的输出:

app/models/test.php (line 299)
Array
(
[0] => Array
    (
        [name] => Alege din 3
        [count] => 8
        [correct] => 2
        [id] => 3
    )
[1] => Array
    (
        [name] => Alege din 4
        [count] => 3
        [correct] => 2
        [id] => 2
    )
[2] => Array
    (
        [name] => Alege din 6
        [count] => 7
        [correct] => 3
        [id] => 4
    )
[3] => Array
    (
        [name] => Scrie raspunsul
        [count] => 2
        [correct] => 1
        [id] => 1
    )
)

app/models/test.php (line 301)
Array
(
[0] => Array
    (
        [name] => Alege din 3
        [count] => 8
        [correct] => 2
        [id] => 3
    )
[1] => Array
    (
        [name] => Alege din 4
        [count] => 3
        [correct] => 2
        [id] => 2
    )
[2] => Array
    (
        [name] => Alege din 6
        [count] => 7
        [correct] => 3
        [id] => 4
    )
[3] => Array
    (
        [name] => Alege din 3
        [count] => 8
        [correct] => 2
        [id] => 3
    )
)