# Buggy code
def drop(self, codes, level=None, errors="raise"):
    """
    Make new MultiIndex with passed list of codes deleted

    Parameters
    ----------
    codes : array-like
        Must be a list of tuples when level is not specified
    level : int or level name, default None
    errors : str, default 'raise'

    Returns
    -------
    dropped : MultiIndex
    """
    if level is not None:
        return self._drop_from_level(codes, level, errors)

    if not isinstance(codes, (np.ndarray, Index)):
        try:
            codes = com.index_labels_to_array(codes, dtype=object)
        except ValueError:
            pass

    inds = []
    for level_codes in codes:
        try:
            loc = self.get_loc(level_codes)
            # get_loc returns either an integer, a slice, or a boolean
            # mask
            if isinstance(loc, int):
                inds.append(loc)
            elif isinstance(loc, slice):
                inds.extend(range(loc.start, loc.stop))
            elif com.is_bool_indexer(loc):
                if self.lexsort_depth == 0:
                    warnings.warn(
                        "dropping on a non-lexsorted multi-index "
                        "without a level parameter may impact performance.",
                        PerformanceWarning,
                        stacklevel=3,
                    )
                loc = loc.nonzero()[0]
                inds.extend(loc)
            else:
                msg = f"unsupported indexer of type {type(loc)}"
                raise AssertionError(msg)
        except KeyError:
            if errors != "ignore":
                raise

    return self.delete(inds)


# Traceback (pandas.errors.InvalidIndexError)
index = pd.Index(range(3)).repeat(2)

index.drop(1)
Traceback (most recent call last):
[...]
pandas.errors.InvalidIndexError: Reindexing only valid with uniquely valued Index objects

# Fixed code
def drop(self, codes, level=None, errors="raise"):
    """
    Make new MultiIndex with passed list of codes deleted

    Parameters
    ----------
    codes : array-like
        Must be a list of tuples when level is not specified
    level : int or level name, default None
    errors : str, default 'raise'

    Returns
    -------
    dropped : MultiIndex
    """
    if level is not None:
        return self._drop_from_level(codes, level, errors)

    if not isinstance(codes, (np.ndarray, Index)):
        try:
            codes = com.index_labels_to_array(codes, dtype=object)
        except ValueError:
            pass

    inds = []
    for level_codes in codes:
        try:
            loc = self.get_loc(level_codes)
            # get_loc returns either an integer, a slice, or a boolean
            # mask
            if isinstance(loc, int):
                inds.append(loc)
            elif isinstance(loc, slice):
                step = loc.step if loc.step is not None else 1
                inds.extend(range(loc.start, loc.stop, step))
            elif com.is_bool_indexer(loc):
                if self.lexsort_depth == 0:
                    warnings.warn(
                        "dropping on a non-lexsorted multi-index "
                        "without a level parameter may impact performance.",
                        PerformanceWarning,
                        stacklevel=3,
                    )
                loc = loc.nonzero()[0]
                inds.extend(loc)
            else:
                msg = f"unsupported indexer of type {type(loc)}"
                raise AssertionError(msg)
        except KeyError:
            if errors != "ignore":
                raise

    return self.delete(inds)