Supposedly, 'every picture tells a story' - 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 (below) 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 together tell the story.

Market Grandma

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.

Watching Life

Completing the Story

Neither of these two photos is particularly compelling - but together, they tell a story.  A good example of making something from very little.

Once upon an afternoon in San Francisco

Incidentally, it's easy to create diptych photos like this if you have Lightroom and Photoshop.  Just select the two photos in Lightroom, then choose "Edit ->  Open in Photoshop as Layers." Then move the layers to where you want them. Give each layer a trim, and place a background (I've used white here).  When you are finished, in Photoshop just select "Close"  (Command + W on a Mac) and you'll be prompted to save the diptych. It will then automatically appear back in Lightroom.