Not precisely a bug but, I think it belongs here. The script in question is:
Submit Once! Form validation. There is nothing technically wrong with that page, the trouble arises on its Developer's View page:

Home > Form Effects > Submit Once! Form validation > Developer's View (http://www.dynamicdrive.com/dynamicindex11/submitonce_dev.htm)

That code does not work, it is missing two things, at the end of the script it needs this:
}
}
return false
}
</script>instead of the current:
}
}
}
</script>and in the markup it should read:
<form onSubmit="return submitonce(this)">instead of this:
<form onSubmit="submitonce(this)">