In my case those seem to get created when I expand my clusters with new nodes (maybe you also did recently?). Additionally, those strange entries are not only there for the nodes, but also for the LIFs.
Looks like ONTAP creates such entries - temporarily - when cluster gets expanded. Those are available - again, temporarily - in statistics subsystem and therefore get fetched by Harvest. We would not even notice normally, but Harvest does notice many things checking the cluster every 1 minute :).
Assuming those temporary entries are required for cluster internal reasons a workaround could be to stop the Harvest poller for the time of cluster expansion.