Adding two of the same sequences together fails

[bbollen23]

    # works
    first_seq = rvt.sequence(order='fixed', components=[comp_one])
    second_seq = rvt.sequence(order='fixed', components=[comp_one])
    sequence = first_seq + second_seq


    # doesn't work
    first_seq = rvt.sequence(order='fixed', components=[comp_one])
    sequence = first_seq + first_seq