The variables are submitted via POST and then POST is copied to $_SESSION[_POST].
When I run the first form I can see that $_SESSION['_POST'] contains the data I want and I can refer to it in the output of the first form. However when I submit the second form I lose the data from the first form and $_SESSION['_POST'] only contains the data submitted by the second form - but I still need to display some of the data submitted from the first form.
I could see why this would be the case if I was only referring to the $_POST superglobal but when I've copied everything to $_SESSION shouldn't the data from the second form just be added as new array elements to $_SESSION['_POST'] rather than it all being removed?
All the other data I need is still present in $_SESSION, its just the data in $_SESSION['_POST'] that is being reset for some reason.
I suppose I could rename the $_SESSION['_POST'] to something else and then refer to this but this seems messy since I don't undertand why its not working the way I though it should