I think scientific theory demands bringing home a FOF, removing the fish from the sandwich, putting it on a plate next to a Gorton's, and finding out exactly what the difference is in the filet itself.
One could likewise compare the two tartar sauces.
That's tantamount to wasting a FOF, since one isn't likely to reconstruct the sandwich after all of that. But there are times when sacrifices must be made in the name of SCIENCE.