Well, now that you mention it…
It seems like Photolab 8 allows you to compare two images. Has anyone tried it?
On the website you’ll find a download link for a trial version. Better test for yourself then rely on the impression of others 
Yes. It works, and I am very grateful (and subsequently purchased PL8).
You right-click an image, select “Use as Reference Image,” and can them scroll through your filmstrip and select one you wish to edit, with the Reference image stuck next to it (or above it, or over it…you can alter that behavior in the upper menu or with keyboard shortcut SHIFT^C).