google is reported to be working on a new feature for Google Photos that will help clean up and organize your library. Called Photo Stacks, the name is literal, taking similar photos that were taken together and automatically grouping them into a stack.
Detailed by user @AssembleDebug over on the service formerly known as Twitter, strings of code for this presumably upcoming feature also say that users can edit stacks and change the “top pick,” as well as turn Photo Stacks on/off, which leads us to believe it's not going to be enabled by default.
These strings were discovered in v59 of Google Photos, but nothing is live quite yet.
We'll stay on the lookout for it.