This may not be a direct answer to your question, but it might help.
Emacs manages its buffer list, including deciding which buffer gets displayed when you kill one (via kill-buffer). I haven't looked into how it's done, but the documentation is "out there". Lots of people have created custom buffer-stack management magic to change the way emacs does things, maybe some of them are based on bayesian analysis, or whatever. You can imagine the possibilities.
I've never looked into changing the way emacs manages its buffers. Instead I just bind other-window and switch-to-buffer to easy keystrokes (C-x o, C-x b) and I get really good at using them.
you could create a simple function for what you want: it should destroys all other windows, then split the window so that the current buffer is displayed in both. Luckily, emacs has functions that do exactly those things.
(defun cheeso-show-buffer-two-windows ()
"Close all other windows; then split, and show the current
buffer in both windows."
(interactive)
(delete-other-windows)
(split-window-vertically))
Bind that to a keystroke, and badda-bing, you're there. This is a vertical split - the windows are displayed in a vertical stack. If you want it horizontally split (the windows are side-by-side), then replace ... well, you know.