Look at the barges I mentioned (https://imgur.com/a/ZNaLCuO). Clearly this specific case isn't an automatic stitching of photos. We must agree that there is only one barge and, though not copied, one instance of the boat has been moved out of line from the other. It would look ugly otherwise.

> Why wouldn't they erase a duplicate?

This I don't have a good reason for, which is why i thought this was curious