Here are two objects with strange tagging overlapping:
https://www.openstreetmap.org/node/3941614242
https://www.openstreetmap.org/node/10744448693
They use amenity=lifeguard and amenity_1=lifeguard. Probably both tags should get removed. Then we would have one amenity=shelter and one emergency=lifegurad. That would make sens. But as I do not know the situation I do not want to make that change.