嵌套的foreach范围中的布尔值给出了意外的值

I have an array of arrays. They are all rows of people that subscribed for a seminar. At the end of the table there are some upsell products added. Problem is: sometimes someone orders for 2 people and the upsell products, that belong to a transaction, not to a person are joined behind both persons. So If I sign up 2 people and buy 2 shirts the list states 2 shirts twice.

So I thought: let's loop through it, see if I find some upsells and then remove every second occurence with a simple double foreach. But the value of $first remains true always. While it is false if I echo it below the declaration. I echoed the values several times and I added the value in comments the code.

foreach($results as $key => $result){
    if(!empty($result["upsell"])){
        $tid = $result["id"];
        $first = true;
        foreach($results as $result2){
            if($result2["id"] == $tid){
                // ALWAYS TRUE
                if(!$first){
                    $results[$key]["upsell"] = "";
                }
                $first = false;
                // FALSE
            }
        }
    }
}

Is there some weird scope thing going on here? In my opinion it should loop first and be true then loop second and be false.

EDIT, added the print_r of results.

Array
(
   [28] => Array
    (
        [id] => 1475
        [transaction_id] => SAME
        [club] => xxxxxxxx
        [event] => Voetbalmiddag 
        [category] => Scoutingdagen
        [date_from] => 2017-05-31
        [date_end] => 2017-05-31
        [first_name] => xxxxxx
        [last_name] => xxxxxx
        [birth_date] => xxxxxxx
        [email] => xxxx@hotmail.com
        [address] => xxxxx
        [zipcode] => 8xxxxx
        [city] => xxxxxx
        [phone] => xxxxxx
        [soccer_club] => xxxxxxx
        [soccer_team] => MP JO7-2
        [position] => field
        [printed] => 0
        [print_name] =>  
        [print_number] =>  
        [shirt_size] => 
        [sock_size] => 
        [pants_size] => 
        [referral] => Via de sportvereniging
        [comments] =>  
        [status] => paid
        [upsell] => 2 Shirt
    )

[29] => Array
    (
        [id] => 1476
        [transaction_id] => SAME
        [club] => xxxxxxx
        [event] => Voetbalmiddag
        [category] => Scoutingdagen
        [date_from] => 2017-05-31
        [date_end] => 2017-05-31
        [first_name] => xxxx
        [last_name] => xxxxxxx
        [birth_date] => xxxxxxx
        [email] => xxxxx@hotmail.com
        [address] => Ixxxxx
        [zipcode] => xxxxx
        [city] => xxxxxx
        [phone] => xxxxx
        [soccer_club] => xxxxx
        [soccer_team] => MP JO9-9
        [position] => keeper
        [printed] => 0
        [print_name] =>  
        [print_number] =>  
        [shirt_size] => 
        [sock_size] => 
        [pants_size] => 
        [referral] => Via de sportvereniging
        [comments] =>  
        [status] => paid
        [upsell] => 2 Shirt
    )

[50] => Array
    (
        [id] => 1468
        [transaction_id] => xxxxxxx
        [club] => xxxxxxxxxxx
        [event] => Voetbalmiddag
        [category] => Scoutingdagen
        [date_from] => 2017-05-31
        [date_end] => 2017-05-31
        [first_name] => xxxxx
        [last_name] => xxxxx
        [birth_date] => xxxxx
        [email] => x@gmail.com
        [address] => xxxx 35
        [zipcode] => xxxx
        [city] => xxxxx
        [phone] => xxxxx
        [soccer_club] => xxxx
        [soccer_team] => jo11-5
        [position] => field
        [printed] => 0
        [print_name] =>  
        [print_number] =>  
        [shirt_size] => 
        [sock_size] => 
        [pants_size] => 
        [referral] => Via de flyer
        [comments] =>  
        [status] => open
        [upsell] => 1 Shirt
    )

)

...
$first = true;
$results1 = $results;  
foreach($results1 as $result2){
...