I've got a simple form on my page (name, email and how you found me) which works fine and writes the details to a txt file once the form has been submitted. However, I seem to be getting people you submit the form and then refresh the page (for whatever reason) and their details get added again to the txt file.

My question is: Is there a way to check if a person refreshes the screen and if they have bypass the writing to the txt file routine?