def METHOD_NAME(exc):
    """
    Returns True if the given exception indicates that there was an attempt to save a User record with an
    already-existing username.
    Args:
        exc (Exception): An exception
    Returns:
        bool: Whether or not the exception indicates a duplicate username error
    """
    return re.search(r"\(username\)=\([^\s]+\) already exists", str(exc)) is not None