.inc files doubles up

This is really my first major PHP encounter, and I have attempted to modify a php form mail script to include a foot.inc and head.inc file, which works fine if all required fields in the form is filled out. But if there are more than 2 required fields missing I end up with what you see here: http://komposlo.inmono.net/sendform.php Now I can understand why that is, but how do I write a command that includes the head/foot.inc file on certain conditions, so it isn't multiplied like seen at the above mentioned site? Again, all help is appreciated