Invalid "overloaded function signature will never be matched"

Bug Report

When trying to use typing.overload with frames from the astropy project (https://www.astropy.org/), incorrect errors are reported by mypy.

To Reproduce

from typing import overload

from astropy.coordinates import GCRS, ITRS


@overload
def f(frame: ITRS) -> None:
    ...


@overload
def f(frame: GCRS) -> None:
    ...


def f(frame: ITRS | GCRS) -> None:
    ...

Expected Behavior

No error.

Actual Behavior

Second overload generates

test.py:12: error: Overloaded function signature 2 will never be matched: signature 1's parameter type(s) are the same or broader  [misc]

Your Environment

• Mypy version used: 1.151
• Mypy command-line flags:
• Mypy configuration options from mypy.ini (and other config files): warn_return_any = true and warn_unused_configs = true
• Python version used: 3.10.5

Start by running the minimal reproducer with mypy and compare the overload-matching diagnostic against the expected behavior. Trace the type-checking path responsible for reporting an overload as unreachable, then add a regression test based on the ITRS and GCRS example; done means the test passes without the erroneous error.