from typing import List
import random


def shuffle_concurrent_lists(l: List[List[object]]):
    """
    Shuffles multiple concurrent lists so that pairs of (x, y) from different lists are still at the same index.

    :param l: A list of concurrent lists
    :return: The list of shuffled concurrent lists
    """

    for x in l:
        random.seed(42)
        random.shuffle(x)

    return l