creating multi-page form token?

[eluser]CI_avatar[/eluser]
1. how to avoid resending of inputs:
You can prevent resending the inputs from your form by using redirection.

2. how to catch pressing back button

you are in current page form then you click submit
then current page = next page

after submit make a SESSION or COOKIE of the to save the current page.
every time the user refresh or click the back button, verify and redirect the user to the current page.