https://www.inaturalist.org/pages/responses#dupe
Duplicate Observations
Duplicate observations can be a burdensome issue for identifiers and data users. Most users don't mean to upload duplicate observations and they typically stem from errors or a misunderstanding that observations should include only a single photo. If observations are flagged, they become casual grade, so many users will flag duplicate observations when they come across them (Select "Other": with comment "duplicate"). This is not officially sanctioned by the iNaturalist staff, but unfortunately no other tools have been provided to address this common data issue. Please only flag the observation if you have informed the observer that it is a duplicate. Of the two or more duplicated observations, the recommended one to flag is the newer one, or the one that is more incomplete (e.g. missing a date, location, or has fewer IDs/comments). See related discussion on the forum.
Exact Duplicates (same photos): This observation appears to be the same as another observation you have uploaded. I have flagged this as a duplicate. In the upper right corner of the observation page, you can click the downward arrow next to "Edit" and choose "Delete." Thank you!
Near Duplicates (same organism but different photos): It looks like you uploaded another observation of this organism at the same time. It's recommended to combine the photos into a single observation rather than to add separate observations of the same thing. I recommend deleting this one and adding the photo to the other observation. Thank you!
[link to other observation(s)]