is it possible to have two input fields per label in a Drupal form?
You cannot have a label for two form fields, as the label is output with HTML code similar to the following one.

&lt;label for="edit-category"&gt;Category: &lt;span class="form-required" title="This field is required."&gt;*&lt;/span&gt;&lt;/label&gt;


The attribute for accepts a single form element ID; you cannot use the following HTML, for example.

&lt;label for="edit-category edit-recipients"&gt;Category/Recipients: &lt;span class="form-required" title="This field is required."&gt;*&lt;/span&gt;&lt;/label&gt;


If you don't want to use a label for the second form element, you can simply use an empty string for the #title property.

As for saving those values in the database, a label is not used when saving the value of a form element, but it is used only on the user interface. The code for saving the content of a form element doesn't use the label value, but the identifier associated to the form element.
In your case, the form submission handler would get the value entered from the user for the $form['example_textfield'] element from $form_state['values']['example_textfield'] where in Drupal 5 would have used $form_values['example_textfield'].