Help! Back button - Redesign Project???

Hello -

Thought I was almost done with my project and then a back arrow button issue
raised its ugly head.

Once a user fills out a form and submits it (done via stored procedure into
a Sql Server database), what's to prevent them from pressing the back button
and resubmitting the form multiple times and creating havoc with my database?
How is this issue usually handled?

Any help will be greatly appreciated!
--
Sandy
.