Question: I have created a basic page which I only want to be viewable by people who have access to the administration theme. 

I have given the page a path of admin/shipping-help but to my surprise the page is visible to anonymous visitors, nor does the page display in the admin theme.

What am I doing wrong?

Answer: 
You can try the [Hide Submit](https://www.drupal.org/project/hide_submit) moddule:

> 
> Some users accidentally click the submit button more than once while
>  waiting for their post to be saved. In some cases this may result
>  duplicate postings or duplicate e-commerce orders.
> 
> 
> There are few ideas on how to solve duplicate postings but none is
>  perfect. One of the solutions is a bit of jQuery to hide or disable
>  the submit button after it has been clicked and replace it with an
>  informative text such as "Processing..." .
> 
> 
> This module wraps that jQuery code and provides some options. Of
>  course this, too, is not a perfect solution as it requires Javascript
>  to be enabled. For browsers with Javascript disabled this module will
>  have no effect at all.
> 
> 
>
Given that you'd like to avoid form submissions with similar data (which really means a combination of fields that are unique), I think the best option would be the [Entity Unique](https://www.drupal.org/project/entity_unique) module.