It would be nice to have a feature to merge and fix observations based on several images of the same individual. This seems to come up every now and then (latest instance here). I consider these “split observations” rather than straight-up duplicates. I imagine one way this could be done is by having a function in batch edit mode where one could select multiple images and click a “merge selected” button, for example.
For organisms with several identifying features spread over multiple observations, having the pictures together in one place would help with IDs. As an identifier, I’ve experimented with an “identical observation set” field as a way to collate several observations that were taken at the same location and time and obviously the same organism. It requires attention to details and is a bit of a guessing game with unresponsive observers, and not every observer allows others to add observation fields.