It's just "Sugarloaf" on the map so remove the "Mountain" part. There are way too many "Sugarloaf Mountain" names in the U.S.
Also, Sugarloaf isn't even on Whidbey Island. It's on Fidalgo Island.
Corrections have been noted. Agree on the that name being used way too must. They would have been better to name it Fidalgo Peak or something more creative. The area is loaded with possibly better names.