False positive "Overloaded function signature 2 will never be matched: signature 1's parameter type(s) are the same or broader" when using Unions vs TypeVars

Bug Report
When overloading a function to specify it can return bytes if given only bytes objects, str if given only str objects, or either if given a mix of both, mypy incorrectly complains that AnyStr is the same or broader than Union[str, bytes].

Despite the warning, mypy does correctly match the Union[str, bytes] signature when appropriate

To Reproduce

Very simple test case:

from typing import overload, TypeAlias, Union, AnyStr, reveal_type
from collections.abc import Sequence
from random import choice

AllStr: TypeAlias = Union[bytes, str]

# Below produces "error: Overloaded function signature 2 will never be
# matched: signature 1's parameter type(s) are the same or broader
# [misc]"
@overload
def pick_three(choices: Sequence[AnyStr]) -> AnyStr: ...
@overload
def pick_three(choices: Sequence[AllStr]) -> AllStr: ...
def pick_three(choices: Sequence[AllStr]) -> AllStr:
    return choice(choices)

strings: tuple[str, ...] = ('abc', 'def')
byte_strings: tuple[bytes, ...] = (b'abc', b'def')
mixed_strings: tuple[AllStr, ...] = ('abc', b'def')

reveal_type(pick_three(strings))  # str
reveal_type(pick_three(byte_strings))  # bytes
reveal_type(pick_three(mixed_strings))  # Union[bytes, str], despite the warning

Some more example code on mypy Playground, with other related cases that work as expected.

Expected Behavior

Mypy does not warn that signature 2 cannot match, given it clearly is able to match based on the reveal_type(pick_three(mixed_strings)) output

Actual Behavior

main.py:39: error: Overloaded function signature 2 will never be matched: signature 1's parameter type(s) are the same or broader  [misc]
main.py:43: note: Revealed type is "builtins.str"
main.py:44: note: Revealed type is "builtins.bytes"
main.py:45: note: Revealed type is "Union[builtins.bytes, builtins.str]"

Your Environment

Seen on Debian with Python 3.11 and mypy 1.0.1 using --strict, and in mypy Playground with Python 3.11 and mypy 1.4.1 with default options.

Inizia riproducendo l'esempio in main.py con Python 3.11 e mypy 1.4.1 o versioni successive, usando gli overloads e le chiamate a reveal_type mostrati nel report. La correzione è completata quando la chiamata con stringhe miste continua a rivelare Union[bytes, str], mentre mypy non segnala più che overload signature 2 non verrà mai abbinata.