I'm pretty sure this is the only page on the Internet that I could not possibly want to see in the new window, since I already had it open.
Havoc is a smart guy, and usually he's right in the money, but he is soooo wrong on this one.
First, it's not always the case that you do not want to see the same page on the new window. You may want to check the bottom of the page to have a window with the footnotes, but still retain a window on the current reading position. But granted it's extremelly rare.
The thing that is invaluable is having the whole history of previous / next links on the new window. When you create a new window it's usually just because you want to fork your lecture. You have found two interesting links to follow on the same page, for instance. In no way is one of the windows more important than the other one to the user. Both are part of the current lecture “tree”.
All the Mozilla derivated I've seen handles new windows (or tabs) from a programmer point of view. They are just new, virgin, history-less windows. A pity.