Duplicating code while using Cache with Decorator pattern [PHP]

I have a Provider class and decorating one, CacheProviderDecorator class. The trouble is that I need to cache the result of method, which is called inside of other provider's method:

For example, in Provider class:

    public function getUser(int $id): array
{
    return json_decode($this->client->get('user/' . $id)->getBody()->getContents(), true);
}


    public function getUsers(array $usersIds): array
{
    $usersSurnames = new Collection();

    foreach ($usersIds as $userId) {
        $usersSurnames->push($this->getUser($userId)['surname']);
    }

    return $usersSurnames->toArray();
}

CacheProviderDecorator class:

    public function getUser(int $id): array
{
    $key = self::PROJECT_USER . '_' . $id;

    return $this->cache->remember($key, self::TTL, function () use ($id) {
        return $this->provider->getUser($id);
    });
}

And because of getUser() is only used inside of getUsers(), I have to duplicate getUsers() method from Provider, else the Provider's getUsers() will be always called, and Provider's getUser() then too (because of $this->).

There are a plenty of such repeats. Is there any good architectural solution instead?