Login page and registration if already connected

In case you are already logged in, visiting the page / page / create-account gives an error "Your current membership (Standard) does not allow you to 'Create Account'." and the visit of the page / page / login gives a blank page, in both cases it is confusing.
Normally this case should not happen except that people regularly put one of his two pages in their favorites.
So I suggest that, if so, either a specific "You are already logged in" message appear on these two pages, or perhaps better, a redirect to the home page in these two cases?