the code to edit is not in the insert behavior, it is in the unique value validation code:
change:
$WAFV_Errors .= WAValidateUnique("CommSimpleRegister",$CommSimpleRegister,$database_CommSimpleRegister,"test_table","email","',none,''","0","email","',none,''","".(((isset($_POST["email"]))?$_POST["email"]:"")) ."",true,3);
to:
$WAFV_Errors .= WAValidateUnique("CommSimpleRegister",$CommSimpleRegister,$database_CommSimpleRegister,"test_table","email","',none,''","0","email","',none,''","".(((isset($_POST["email"]) && $_POST["email"] != ""))?$_POST["email"]:"123456789") ."",true,3);