Why should I write the font size of this CSS file twice?

The font of this CSS file - Why write two? As shown below, font in media - Size is written once in PX and VW. What's the effect of this?

html {
  font-size: 13.33333vw
}

@media screen and (max-width: 320px) {
  html {
    font-size: 42.667px;
    font-size: 13.33333vw
  }
}

@media screen and (min-width: 321px) and (max-width: 360px) {
  html {
    font-size: 48px;
    font-size: 13.33333vw
  }
}

@media screen and (min-width: 361px) and (max-width: 375px) {
  html {
    font-size: 50px;
    font-size: 13.33333vw
  }
}

@media screen and (min-width: 376px) and (max-width: 393px) {
  html {
    font-size: 52.4px;
    font-size: 13.33333vw
  }
}

@media screen and (min-width: 394px) and (max-width: 412px) {
  html {
    font-size: 54.93px;
    font-size: 13.33333vw
  }
}

@media screen and (min-width: 413px) and (max-width: 414px) {
  html {
    font-size: 55.2px;
    font-size: 13.33333vw
  }
}

@media screen and (min-width: 415px) and (max-width: 480px) {
  html {
    font-size: 64px;
    font-size: 13.33333vw
  }
}

@media screen and (min-width: 481px) and (max-width: 540px) {
  html {
    font-size: 72px;
    font-size: 13.33333vw
  }
}

@media screen and (min-width: 541px) and (max-width: 640px) {
  html {
    font-size: 85.33px;
    font-size: 13.33333vw
  }
}

@media screen and (min-width: 641px) and (max-width: 720px) {
  html {
    font-size: 96px;
    font-size: 13.33333vw
  }
}

@media screen and (min-width: 721px) and (max-width: 768px) {
  html {
    font-size: 102.4px;
    font-size: 13.33333vw
  }
}

@media screen and (min-width: 769px) {
  html {
    font-size: 102.4px;
    font-size: 13.33333vw
  }
}