I followed the procedure in your original post.
On my Razor sandbox site I created two new pages.
In the Layout Options metabox for the first page I set the Layout option to reference a “Full Width” layout that in turn references a header named “Minimal Header”.
In the Layout Options metabox for the second page I set the Layout option to reference a “Page – Right Sidebar” layout that in turn references a header named “Default Header”.
These two headers reference different static blocks that display different images.
The result is that both pages are displayed with the correct different body layouts (one full width and the other with a right-hand sidebar), and both pages are displaying the correct different headers.
So that’s working, which means I can’t replicate the problem you are reporting by following the description of the problem in your original post.
Do you have any plugins installed and activated?