The form theming in SF2 uses inheritance. That means that if blocks named email_widget and textarea_widget are defined, neither your e-mail nor your textarea fields will use form_widget. They will rather respectively use their own widget blocks: email_widget and textarea_widget.
Well, in form_div_layout.twig, these two widget blocks are defined. Thus form_widget is not called for 2 of your fields. Thus your message is displayed 2 times instead of 4.
If you want to customize the rendering of these fields, you will have to create your own block definitions email_widget and textarea_widget in your custom form theme file.
Edit:
The default form theme files are defined under Symfony\Bridge\Twig\Resources\views\Form. The default file used is form_div_layout.html.twig.
Although the inheritance logic itself is indeed in the PHP code of the TWIG bridge, it does not define which block inherit from which other block.
Inheritance is actually defined in your FormType classes. Each form type class sports a getParent() method that return the name of the form from which it inherits. The name of a form type is the result of the method getName() of its associated form type class. For instance, with a built-in example, Symfony\Component\Form\Extension\Core\Type\TextareaType:
Textarea >> Text >> Field >> Form
All you have to do is to look for the methods getParent() and getName(). Thus, by default, when rendering the textarea row, Twig will search the block textarea_row, text_row, field_row and finally form_row (the base default row). The first of these blocks that is defined in your form theme is rendered.
The definition of the blocks themselves happen in the form theme files.