How can I avoid repeated triggering of web analytics counter targets?

Question

PHP

The "Order" goal is configured in Yandex.Metrica. This goal is triggered when users open the page with the given address - the order confirmation page. Users get to this page after clicking the "Place an order" button on the page with a shopping cart. The problem is that users can open the order confirmation page several times: for example, by clicking on the "Back" button in the browser. Or by clicking on the link in the newsletter. And if the problem with letters is solved quite simply: by changing the url, then what to do with the "Back" button is not very clear.
Separately, I note that the achievement of the goal is recorded at the moment when the user visits a certain address. The method in which the target is registered by sending an event by js code is NOT used due to its less reliability. At first, we registered the achievement of goals by sending an event on pressing the "Place an order" button, but not all orders were registered.
The site is written in Php.
Question: what are the elegant solutions to the above problem.

Answer 1

Set a parameter in cookies or remember in the session that the button was pressed. When going to the page, check this parameter - if it is, then display it instead of the "Thank you, your order is confirmed" button

Answer 2

Make a page "Thank you! Order completed!" on which the user will get after the successful registration of the order and nail the counter on it?