Refresh-avoidance

I have a form issue that's bugging me. As a part of a user signup, there is a page with a form. The user fills out the form and submits, and all is well, and he gets a confirmation screen, but if he refreshes the confirmation screen (this page contains the script that does the signup work) then a duplicate account is created. I know I can scan for dupes and abort, but is there a simpler way to avoid this? (Like a "refresh-killer"?) TIA -- www.SpamWhack.com A pre-emptive strike against spam A tornado is a lady whose skirts you do NOT want to look up! Where's dave? http://www.findu.com/cgi-bin/find.cgi?kc6ete-9