You can create a single side bar then share that sidebar on many pages as the default side bar, disable the side bar from a page and or set a specific side bar for a page. This is providing you are using the default templates and not the component based templates.
/wp-admin/edit.php?post_type=sidebar
Default side bar
Once you have created a sidebar you can navigate to theme options and assign a sidebar to the default pages and default post (news) single pages.
wp-admin/admin.php?page=amnesty_theme_options_page
This side bar will now show on the default single page and single post (news) pages. This will not work if the page or post is set to a component based template.
Page specific side bar
This can be controlled on the single page/post.
