dataloader batching without caching

index.js

import DataLoader from 'dataloader';

const getBatchUsers = (ids = []) => {
    // runs sth like
    // SELECT * FROM users WHERE id IN (:ids)
};

// cache is disabled
const userLoader = new DataLoader(getBatchUsers, {cache: false});

// Now I'm looping let's say over a list of contacts
const contacts = [
    {
        id: 1,
        userId: 1
    },
    {
        id: 2,
        userId: 1
    },
    {
        id: 3,
        userId: 1
    }
];

const promises = contacts.map(contact => {
    return userLoader.load(contact.userId)
        .then(user => ({
            ...contact,
            user
        }));
});

Promise.all(promises)
    .then(contacts => {
        // I get all my contacts with users loaded
    });

// The issue here is that multiple contacts
// have the same userId and when disabling
// cache the getBatchUsers will be called with [1, 1, 1];
// Basically this will break DataLoader because the query 
// will only return one user instead of 3 (which DataLoader doesn't accept)

// The behaviour I expected was getBatchUsers to get called with [1] only
// It would required to implement a distinct key batching