def _is_extended_mux_needed(messages):
    """Check for messages with more than one mux signal or signals with more than one multiplexer value."""
    for message in messages:
        multiplexers = [
            signal.name
            for signal in message.signals
            if signal.is_multiplexer
        ]

        if len(multiplexers) > 1:
            return True

        for signal in message.signals:
            if signal.multiplexer_ids:
                if len(signal.multiplexer_ids) > 1:
                    return True

    return False