Panel pages also uses the "q" parameter in the URL to define its visibility?

I have 2 administration pages:
http://www.mydomain.com/admin/posts
http://www.mydomain.com/admin/posts/printfriendly

The first one is a simple views page.
The second one is a panel page, with a views block attached.

A user can switch between the 2 pages with URLs at the top, by which I try to preserve the current parameters of the exposed filters in those views.
I should filter more on these preserving on parameters, but somehow I got the following URL:
http://www.mydomain.com/admin/posts?q=admin/posts/printfriendly

Now, when I browse to that URL, I discovered that Panels will read the "q" parameter and show me the second administration page (admin/posts/printfriendly) and not the first one (admin/posts),

Why is this?