You might want to modify your coding. The way I prevent this problem from
ever happening is this:
1. The user completes information on the form.
2. The form is validated by PHP.
3. If there are errors, then the form is reshown with their values
populated.
4. Once all errors are corrected, I process the form and then use a
Header("Location: ") to redirect the user to the same page (or another
page).
This has the advantage of allowing a user to click the back button and
seeing their form with their values still intact.
This prevents a method post page from being in the user's browser history.
