PHP DateTime in Object Doesn't Maintain Original Value In Loop - php

Question

I have array in PHP which contains a date and the amount of days I want to add to that date. As I am looping over these dates and adding the specified amount, the [date] values on each loop keeps getting incremented with each pass of the loop. Here is my array...
Array
(
[0] => Array
(
[date] => DateTime Object
(
[date] => 2017-10-10 06:00:00.000000
[timezone_type] => 2
[timezone] => GMT
)
[daysToAdd] => 3
)
[1] => Array
(
[date] => DateTime Object
(
[date] => 2017-10-10 06:00:00.000000
[timezone_type] => 2
[timezone] => GMT
)
[daysToAdd] => 5
)
[2] => Array
(
[date] => DateTime Object
(
[date] => 2017-10-10 06:00:00.000000
[timezone_type] => 2
[timezone] => GMT
)
[daysToAdd] => 10
)
)
I am passing all of this data to a function to process it...
->processDates($data);
Inside of my PHP function...
foreach($array['dates'] as $day){
$originalDateTime = $day['date']; # original dateTime
$dateTime = $day['date']; # the dateTime as a new var
$dateTime = $dateTime->modify('+'.$day['daysToAdd'].' days'); // modify the dateTime
print_r([
'originalDate'=>$originalDateTime,
'newDate'=>$dateTime,
]);
}
This is what happens when the first element is ran inside of the function...
!!! The original date is also incremented by the value passed when I added it back to the array, even though i set it as a completely unmodified variable inside of the function !!!
Array
(
[originalDate] => DateTime Object
(
[date] => 2017-10-13 06:00:00.000000
[timezone_type] => 2
[timezone] => GMT
)
[newDate] => DateTime Object
(
[date] => 2017-10-13 06:00:00.000000
[timezone_type] => 2
[timezone] => GMT
)
)
This is what happens when the second element is ran inside of the function...
Array
(
[originalDate] => DateTime Object
(
[date] => 2017-10-18 06:00:00.000000
[timezone_type] => 2
[timezone] => GMT
)
[newDate] => DateTime Object
(
[date] => 2017-10-18 06:00:00.000000
[timezone_type] => 2
[timezone] => GMT
)
)
And this is what happens on the 3rd iteration...
Array
(
[originalDate] => DateTime Object
(
[date] => 2017-10-28 06:00:00.000000
[timezone_type] => 2
[timezone] => GMT
)
[newDate] => DateTime Object
(
[date] => 2017-10-28 06:00:00.000000
[timezone_type] => 2
[timezone] => GMT
)
)
Each time I loop over the array the original datetime gets messed up by the ->modify. How can I prevent this so that each loop completely gets reset and uses the actual data passed in. I need the ['originalDate'] to maintain as originally set as "2017-10-10 06:00:00.000000"...
Thanks.