Duplicate php object into two similar objects

I have an object with some variables for events (id, date, time, etc) gathered from a database. Some events have multiple days per week, so I want to duplicate the event object for each day listed and mark which day it's being duplicated for.

For example, I have this object inside an array:

Array
(
[0] => stdClass Object
    (
        [id] => 1
        [days] => Array
            (
                [0] => Mon
                [1] => Tues
            )
    )
)

and I'd like it to look like this:

Array
(
[0] => stdClass Object
    (
        [id] => 1
        [day] => Mon
        [days] => Array
            (
                [0] => Mon
                [1] => Tues
            )
    )

[1] => stdClass Object
    (
        [id] => 1
        [day] => Tues
        [days] => Array
            (
                [0] => Mon
                [1] => Tues
            )
    )
)

For some reason, when it loops through the second time the object is getting updated in the 0 position of the main array and the 1 position like so:

Array
(
[0] => stdClass Object
    (
        [id] => 1
        [day] => Tues
        [days] => Array
            (
                [0] => Mon
                [1] => Tues
            )
    )

[1] => stdClass Object
    (
        [id] => 1
        [day] => Tues
        [days] => Array
            (
                [0] => Mon
                [1] => Tues
            )
    )
)

This is a replication of the array declaration and loop I'm using:

$out = array();
$arr = array();
$arr[0] = new stdClass();
$arr[0]->id = 1;
$arr[0]->days = array("Mon","Tues");

foreach($arr as $a){
    foreach($a->days as $day){
        $a->day = $day;
        $out[] = $a;
    }
}

I did the same thing with straight arrays (cast the object as an array) and there it worked as I hoped, but it'd be nice to know how to do it with objects as well.

Any ideas?