拉威尔php'；s date_添加函数don'；行不通

使此Laravel播种机功能正常。问题是日期没有按预期改变。如果我在Tinker中运行代码，它就会工作

我做错了什么

public function run() {
    $faker = Faker::create();

    foreach(range(1, 10) as $index)
    {
        $myDateCalled = $faker->dateTime($max = 'now');

        $myDateAllocated = $myDateCalled;
        $i = $faker->numberBetween($min = 5, $max = 300);
        date_add($myDateAllocated, date_interval_create_from_date_string("{$i} seconds"));

        $myDatePickedUp = $myDateAllocated;
        $i = $faker->numberBetween($min = 5, $max = 30);
        date_add($myDatePickedUp, date_interval_create_from_date_string("{$i} minutes"));

        $myDateDelivered = $myDatePickedUp;
        $i = $faker->numberBetween($min = 10, $max = 90);
        date_add($myDateDelivered, date_interval_create_from_date_string("{$i} minutes"));


        dd($myDateCalled, $myDateAllocated, $myDatePickedUp, $myDateDelivered);

        Hhtransport::create([
            'Called' => $myDateCalled,
            'Allocated' => $myDateAllocated,
            'PickedUp' => $myDatePickedUp,
            'Delivered' => $myDateDelivered,
            'From' => $faker->numberBetween($min = 1, $max = 99),
            'To' => $faker->numberBetween($min = 1, $max = 99),
            'Put' => $faker->numberBetween($min = 1, $max = 99),
            'Drev' => $faker->numberBetween($min = 1, $max = 99),
            'Container' => $faker->numberBetween($min = 1, $max = 99)
        ]);
    }
}

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dateTime是一个对象，因此通过引用传递。这意味着我只创建了一个具有4个不同名称的dateTime对象

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使用$myDateAllocated=克隆$myDateCalled；解决了我的问题。

怎么解决？？？。摘自《托图里亚斯》……好吧，也许我遗漏了什么，什么教程是出于兴趣？