The Philippines were named after a Spanish king, King Phillip, or Felippe in Spanish. Given that the country was first controlled by the Spanish for ages, then the Americans, I’m guessing that at first the Spanish name for both the people and the territory was used, but when the Americans took over, the English-ified name of the territory was used, while the Spanish name for the people stuck as colonial powers use the name for the territory more often? Perhaps the Filipino diaspora also plays a role in this. I don’t know, just my guess.