access values from a previous order page

I have a page where users fill out order information.  i.e. name, address, etc.
When the form is complete, user clicks a submit button.  The form is posted to a 3rd party gateway for processing the order and returned to a confirmation or failure page setup on my site.  Technically, the order page is not the most previous page because the order form posts to the 3rd party site but because I pass all the data they require from my form I bypass their screens and their system just returns to my site.  They return successful order to my confirmation page or failure to my failure page.
What I want is to have some of the data from my order page appear on the confirmation such as first name and other order details.  How can I access data from "two" previous pages?
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