I get the same trouble as you, double labels on favorites which are also setup for alerts.
To avoid this, I suggest that you save these location/spots as Alert but not as Favorite
If you save them first as favorite and then set an alert for these favorites, you get the double labels.
So clean off your list of favorites, and save your surfspots as Alert in the small pop up when you click on the heart next to the search box.

Here is an example, where Bergen is a Favorite without setting up an alert, and a location at sea set as an Alert location. There is no double labelling

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