Music21 Instrument Objects not working as expected

Question

I am trying to predict the next musical instrument note pair in python using an RNN neural network. However, I am having trouble interpreting the music21 documentation for the part I am currently on.

In the code below I, am trying to extract the musical instrument.

1. Why am I getting multiple instruments? Ex: Instrument.Piano.Piano.

   • My current theory is that each stream part is returning a different memory address or music21 has multiple variants of these differing instruments. If the second statement holds is there a way of getting uniqueness for each instrument variant?

2. Why do some instruments not have a name of any sort?

   • I have a few ideas of why this is, but I want to confirm with the community to make sure I am still sane.

# Attempt to parse midi file
try:
    midi = converter.parse(file)
except:
    # Midi file couldn't be opened
    return {"song_notes": [],
            "note_count": [],
            "small_file_check": False,
            "corrupted": True}

# Stores all found instruments
instruments_in_song = set()

# Iterate through stream parts
for stream_part in midi.parts:
    stream_instrument = instrument.partitionByInstrument(stream_part)
    if stream_instrument:
        for instr in stream_instrument.recurse().parts:
            print("Instrument: {0}".format(instr.getInstrument()))
            instruments_in_song.add(instr.getInstrument())

print(instruments_in_song)

My file output: