Can you view two Render-Slots at the same time in blender? I know you can save them and use an external viewer; not an eloquent solution however.

When I open up another window, it won't let me view two different
slots.  Each time I change one, the other sync's up.
They appear to be linked somehow.  How do you un-link them?
You cannot view different render slots simultaneously within Blender :-( There are some ways you could "hack" it, like saving it out and loading it into the image editor. But it'd just be a hack.