can one account have more than one address? Bitcoin core support the methods : 

getnewaddress [account]
getBalance [account] [minconf=1]

All of them are base on account concept. So I wonder that if one account can contains more than one address?

When I call the getnewaddress with the same account name many times, what does happen? The account will associate with all addresses that the method created, right?
First of all, do not use the accounts feature. It is both broken and going to be removed. It is important to note that accounts are not part of Bitcoin at all and are just a part of Bitcoin Core.

You can associate multiple accounts with the same address. It just means that the account's balance will update with each amount sent to an address associated with the account. However, sending Bitcoin from an account in your wallet WILL NOT necessarily "send from" the addresses associated with the account. It will just decrease the balance of that account.