1つのゲームオブジェクトから複数の同一コンポーネントを取得

private EnemyManager[] scripts;
private const int INTERVAL_UPDATE = 100;
private int nextTargetScore = INTERVAL_UPDATE;

void Start() {
    scripts = GameObject.Find("EnemyManager").GetComponents<EnemyManager>();
}

void Update() {
    // 100ptごとにspown率を更新
    if(score >= nextTargetScore){
        nextTargetScore += INTERVAL_UPDATE;
        foreach (var script in scripts)
        {
            script.UpdateSpown();
        }
    }
}