a:
  b: 1
  c: 2
d:
  e: 3
  f: 4
  duplicate: # 1
    id: 1234
    note: "this is the first one, so it won't raise an error"
  duplicate: # 2
    id: 5678
    note: "this is the second one, so it will raise an error, hopefully at the start of the key"
g:
  h: 5
  i: 6
