Supposedly, 'every picture tells a story' ("don't it!"). But sometimes it take two. Here are a few examples of where the diptych comes in handy.
Before and After
When I first approached this woman in Saigon to take her photo, she wasn't sure what to make of me. I then showed her the first photo in the preview panel of my camera. She burst out laughing. Okay, that was not a confidence builder. But I quickly turned the camera around and got the second photo. To me, the two tell the story.
Same Person, Different Day
No, I didn't ask this fellow to change into pink pajamas. I just happened to catch the first shot and liked it, as a stand-alone. Several days later, I was passing the same bridge and - without realizing who it was - took another photo of an interesting old man in pj's. It was not until I was looking at the collection that I realized it was the same man! I've been back to that bridge several times. Never saw him again.
Completing the Story
Neither of these two photos are particularly interesting - but together, they tell a story. A good example of making something from very little.