Just recently I found myself in a situation where I couldn't decide which of two images was the keeper and which was the second. In the end I decided they would both be my seconds. Here's what I mean.
A recent visit from my grandson, Evan, required me to pull out my camera, of course. Our local fire department had just driven by, handing out candies and popcorn balls to the neighborhood kids. Evan was halfheartedly munching on one of them and during a lull in the day's activities I caught a tender moment between Evan and my wife on our front porch. I took two shots before Evan got his second wind and went off to another activity. Looking at the two images I saw potential in them but did not liked either of them on their own.
Fortunately, with the magic of image editing and luck that the two frames had been taken within seconds of each other, it made it easier to merge the two shots. The only viable solution to salvaging this shot.
How it was done
The two images were opened as layers and auto aligned in Photoshop (see first image at top). A layer mask on the top image makes quick work of changing my wife's expression from the first to the second image, altering the entire mood of the scene.