I have a submit button at the end of the form.
I have added the following condition to the submit button:
onClick=\"this.disabled=true; this.value=\'
Another solution i´ve used is to move the button instead of disabling it. In that case you don´t have those "disable" problems. Finally what you really want is people not to press twice, if the button is not there they can´t do it.
You may also replace it with another button.