There's a possibility that the acpi-support scripts also catch these events and duplicate the key presses.
Can you please try
sudo dpkg -P acpi-support
and check if it still behaves the same?
However, that wouldn't explain the irregular behaviour you sometimes get, like endless number of repeats.
udev's keymap itself seems to be right here (or, rather, not affected at all), the key symbols seem to be correct. So if acpi-support isn't the culprit, this would be a kernel bug.
There's a possibility that the acpi-support scripts also catch these events and duplicate the key presses.
Can you please try
sudo dpkg -P acpi-support
and check if it still behaves the same?
However, that wouldn't explain the irregular behaviour you sometimes get, like endless number of repeats.
udev's keymap itself seems to be right here (or, rather, not affected at all), the key symbols seem to be correct. So if acpi-support isn't the culprit, this would be a kernel bug.