KeyAlreadyPresent when accessing valid TOML with repeated array tables under an out-of-order table #505

Description

tomlkit.parse() accepts a TOML document, but later accessing a parsed table with doc.get("hooks") can raise:

tomlkit.exceptions.KeyAlreadyPresent: Key "Stop" already exists.

This happened with a valid TOML config that contains repeated array tables such as [[hooks.Stop]] plus sibling/subtables under [hooks].

The failure appears to happen while constructing an OutOfOrderTableProxy, not during parsing.

Observed behavior
This code path fails:

import tomlkit
from pathlib import Path

text = Path("config.toml").read_text(encoding="utf-8")

doc = tomlkit.parse(text)      # succeeds
hooks = doc.get("hooks")       # raises KeyAlreadyPresent

Traceback:

Traceback (most recent call last):
  File "<string>", line 11, in <module>
  File "<frozen _collections_abc>", line 807, in get
  File ".../tomlkit/container.py", line 711, in __getitem__
    item = self.item(key)
  File ".../tomlkit/container.py", line 517, in item
    return OutOfOrderTableProxy(self, idx)
  File ".../tomlkit/container.py", line 912, in __init__
    self._internal_container._raw_append(k, v)
  File ".../tomlkit/container.py", line 360, in _raw_append
    raise KeyAlreadyPresent(key)
tomlkit.exceptions.KeyAlreadyPresent: Key "Stop" already exists.

Expected behavior

If tomlkit.parse() accepts the TOML document, then accessing doc.get("hooks") should not fail with KeyAlreadyPresent.

Repeated array tables like this are valid TOML:

[hooks]

[[hooks.Stop]]
matcher = ".*"

[[hooks.Stop.hooks]]
type = "command"
command = "one"
# even some actual content in here is valid but tomlkit gives an issue if something else is present
[[hooks.Stop]]
matcher = ".*"

[[hooks.Stop.hooks]]
type = "command"
command = "two"

[hooks.state]

[hooks.state.example]
trusted_hash = "sha256:abc"

Actual behavior
On the original config, tomlkit.parse(text) succeeded, but doc.get("hooks") raised KeyAlreadyPresent: Key "Stop" already exists.

Versions tested
This reproduces with:

Python 3.12.7
tomlkit 0.14.0
tomlkit 0.15.0
tomlkit 0.15.0 produced the same class of traceback:

0.15.0
tomlkit.exceptions.KeyAlreadyPresent: Key "Stop" already exists.

Notes
The issue seems related to OutOfOrderTableProxy handling repeated array tables under a table that also contains sibling tables/subtables. Reordering the TOML so repeated [[hooks.Stop]] entries are grouped before other sibling tables avoids the failure in my application, but the original TOML should still be accessible after parsing.