This page looks secure to me, unless someone is manually spamming it. Are you sure it is from this page? Maybe add a page identifier with the insert to make sure you are looking at the page causing the issue.
When you try it, can you get it to insert without entering the correct security answers? I don't see any way someone could circumvent it, if it works for you. If it doesn't validate correctly with the wrong answers then I must be misssing something and let me know and I'll look more carefully for issues, but this looks secure to me.