Description:
------------
When PHP parses url with parse_str() to populate $_POST/$_FILES on multipart/form-data,PHP merges same keys into one value, its known behavior.

I tried to fill form fields after redirect from POST to GET with validation error. When merged - it's not possible. Would be great to have $_FORMDATA that should looks like this (opinion): 

[
  ['hello[name][]', 123],
  ['hello[name][]', 123],
  ['hello[]', 123],
  ['hello[]', 123],
  ['hello', 123],
]

because $_POST will looks like [ 'hello' => 123 ]

Problem happened when we work with multifields (button '+ add field') or multiselects - where we should set "selected" for its options

Test script:
---------------
// get.php

<form method="POST" type="multipart/form-data">
  <select multiple="multiple" name="hello[name][]">
    <option value="123">123</option>
  </select>
  <input type="text" name="hello[name][]" value="123" />
  <input type="text" name="hello[name][]" value="123" />
  <input type="text" name="hello[]" value="123" />
  <input type="text" name="hello[]" value="123" />
  <input type="text" name="hello" value="123" />
  <button type="submit">Send</button>
</form>

// post.php
var_dump($_POST);

Expected result:
----------------
var_dump($_POST);
[ 'hello' => '123' ]

var_dump($_FORMDATA);
[
  ['hello[name][]', 123], // select(multiple)
  ['hello[name][]', 123], // input[]
  ['hello[name][]', 123], // input[]
  ['hello[]', 123], // input[]
  ['hello[]', 123], // input[]
  ['hello', 123], // input
]