Hello there :)

If you look closely you'll find a point (node) that shows up with a lightning symbol when you edit the map where you put the watermill. This node is already tagged as watermill and also as a generator. That's why it's not immediately clear the mill is already mapped.

Since your new node did not offer any new information at this location I took the liberty of removing it.

Should you have any questions, please ask

cheers
silversurfer83
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            Published using OSMCha: https://osmcha.org/changesets/159645179
            