Firestore Array of map not updating

So I’m working on a personnal project to learn react-native and firestore.

I have a a DB like this:

and I want by code to add a new battery in the array batteries.
The elements in the array are just a map{string, string}

The problem is that when I update the array with a new brand that’s work but if I want to update it with the same brand again have,
so having by the end

batteries[0]: {'brand': 'cestmoi'}
batteries[1]: {'brand': 'cestmoi'}

the db doesn’t update, don’t have any error or so.

I don’t understand why and I followed their tuto. Here is my code:

async function addData(collection, doc, value) {
    console.log(`Add data ${value.brand}`)
    try {
        const result = await firestore()
                    .collection(collection)
                    .doc(doc)
                    .set({
                        batteries: firestore.FieldValue.arrayUnion(value)
                    })
        console.log(result);
        return result;
    } catch (error) {
        return error;
    }
}

I use try catch by habit but I don’t know if the then...catch is better or not…

Thanks