In HTML 5 you can use the h1 element multiple times. For example, lets say you are writing an article

  article
    h1
    h2

That is perfectly valid, now lets say you have an header that gets added before each article that contains some information such as author, time created/published

  header
    timedate
    h1 
      Article Title
    author
  article
    h1
    h2

This is valid HTML 5.