I wrote JSON::MultiValueOrdered to cope with JSON like the following:

{
  "foo": 1,
  "bar": 2,
  "foo": 3
}
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If you parse the above into $data then $data->{foo} will be 3, but tied(%$data)->get('foo') in list context will return ( 1, 3 ), and if you serialize the structure, you'll get this, preserving the original order of the keys:

{
  "foo": 1,
  "bar": 2,
  "foo": 3
}
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