对Console.ReadLine()的困惑

 为什么下面的文字会出现2次？ 
           1.存款
           2.取款
           3.查询余额
           4.修改密码
           5.退出
-----------------------------------------------
你的选择（回车结束）：
           1.存款
           2.取款
           3.查询余额
           4.修改密码
           5.退出
-----------------------------------------------
你的选择（回车结束）：有4个类：
namespace ATM
{  
    class Start
    {
        static void Main(string[] args)
        {
            Bank bank = new Bank("交通银行");
            Atm atm = new Atm(bank);
            atm.Start();
        }
    }
}
namespace ATM
{
    class Account
    {
        protected string name;
        protected string password;
        protected decimal balance;        public Account(string name, string password)
        {
            this.name = name;
            this.password = password;
            this.balance = 0;
        }        public string Name
        {
            get
            {
                return name;
            }
        }
        public decimal Balance
        {
            get
            {
                return balance;
            }
        }        public bool Deposit(decimal amount)
        {
            if (amount <= 0)
            {
                return false;
            }
            balance += amount;
            return true;
        }
        public bool Deposit(double amount)
        {
            return Deposit((decimal)amount);
        }
        public bool Deposit(int amount)
        {
            return Deposit((decimal)amount);
        }
        public bool Deposit(decimal amount, out decimal balance)
        {
            bool succeed = Deposit(amount);
            balance = this.balance;
            return succeed;
        }        public bool Withdraw(decimal amount)
        {
            if (amount > balance || amount <= 0)
            {
                return false;
            }
            balance -= amount;
            return true;
        }
        public bool Withdraw(double amount)
        {
            return Withdraw((decimal)amount);
        }
        public bool Withdraw(int amount)
        {
            return Withdraw((decimal)amount);
        }
        public bool Withdraw(decimal amount, out decimal balance)
        {
            bool succeed = Withdraw(amount);
            balance = this.balance;
            return succeed;
        }        public bool Login(string name, string password)
        {
            return (this.name == name && this.password == password);
        }        public bool ChangePassword(string oldPassword, string newPassword)
        {
            if (password != oldPassword)
            {
                return false;
            }
            password = newPassword;
            return true;
        }
        
    }
}
namespace ATM
{
    class Bank
    {
        protected const int MaxAccountNum = 2048;
        protected string name;
        protected int usedAccountNum;
        protected Account[] accounts;        public Bank(string name)
        {
            this.name = name;
            this.usedAccountNum = 0;
            accounts = new Account[MaxAccountNum];
        }        public string Name
        {
            get
            {
                return name;
            }
        }        public bool LoginAccount(string name, string password, out Account account)
        {
            account = null;
            for (int i = 0; i < usedAccountNum; i++)
            {
                if (accounts[i].Login(name, password))
                {
                    account = accounts[i];
                    return true;
                }
            }
            return false;
        }        public bool OpenAccount(string name, string password, out Account account)
        {
            account = null;
            for (int i = 0; i < usedAccountNum; i++)
            {
                if (accounts[i].Name == name)
                    return false;
            }
            account = new Account(name, password);
            accounts[usedAccountNum++] = account;
            return true;
        }
    }
}