def sgi_1973_to_2016(sgi_id: str) -> str:
    """
    Convert the slightly different SGI1973 to the SGI2016 id format.
    
    :examples:
        >>> sgi_1973_to_2016("B55")
        'B55'
        >>> sgi_1973_to_2016("B55-19")
        'B55-19'
        >>> sgi_1973_to_2016("E73-2")
        'E73-02'
    """
    if "-" not in sgi_id:
        return sgi_id

    start, end = sgi_id.split("-")
    return start + "-" + end.zfill(2)