Bitrix and Yandex checkout, why different order numbers?

Question

1C-Bitrix

Good day ! The site has a multi-site functionality, two IMs on which you can place orders, Yandex checkout is connected. Links are registered in the Yandex checkout account:

Check URL https://site1.ru/bitrix/tools/sale_ps_result.php

Aviso URL https://site1.ru/bitrix/tools/sale_ps_result.php

Success URL http://site1.ru/bitrix/tools/sale_ps_success.php

Fail URL http://site1.ru/bitrix/tools/sale_ps_fail.php

i.e. links from the first site, when the client makes an order on the second site site2.ru, then in case of successful payment, respectively, it gets to site1.ru , I need to redirect to site2.ru i.e. to the site where the order was made .
In the /bitrix/tools/sale_ps_success.php file, I want to make a redirect, as it seemed to me that this can be done by getting the order ID from the URL that Yandex Checkout generates in case of successful payment, which has the orderNumber=273 parameter .
I noticed that the order number in Yandex checkout does not match the order number on the site. For example, if a YAK is 273, then on the site it is 280.
And the result of what I want to do:
Get the order number from the URL, in the file sale_ps_success.phpcheck which site the order belongs to and redirect to the correct site https://site2/personal/order/make/?ORDER_ID= ".$OrderID
Has anyone else experienced this? Why are the order numbers different?

Answer 1

Because Bitrix has released the possibility of partial payment. And Yandex checkout returns the id of this payment.