I have created a token with Token name as TestToken and Symbol as TTT for crowd-sale. During Crowd-sale I have transferred TTT token to my investors say Bob. After crowd-sale, he (Bob) transferred TTT token to his friend Alice. Now, How to ensure Alice Token TTT was created by me? What if he created another token contract with the same name and symbol and claim that was the original token. How to differentiate original one and false token? And how to track my token flow after crowd-sale.
What if he created another token contract with the same name and symbol and claim that was the original token. How to differentiate original one and false token?
It's important to understand how an ERC20 token on Ethereum works: each contract is its own individual ledger maintaining the balances (number of tokens) that a given address holds.
Imagine an Excel spreadsheet with two columns; one containing Ethereum addresses and the adjacent one containing numbers: representing the number of tokens that each address owns (usually with the creator's address starting with a number representing all of the tokens in existence). The Spreadsheet is password protected, but contains a small number of Macros that allows someone to update the number in the column adjacent to their Ethereum address.
Now, if someone looks over your shoulder and creates an identical Spreadsheet they can't magically update the values in yours. Even if they name the spreadsheet the same as yours, it's not the same one and only you with your password can modify those initial numbers against the creator's address.
Sure, that person could trick someone into believing that the spreadsheet, named the same as yours, is yours - if the victim believed them purely on the name alone, but this is why we use the more solid, unique and provable address of the Token contract in Ethereum.
And how to track my token flow after crowd-sale.
You could track it by following the events emitted by the contract and/or calling the functions defined in the ERC20 specification.
However, a much easier approach would be to use Ethplorer
For example, EOS looks to currently be the most used ERC20 token and it can be tracked https://ethplorer.io/address/0x86fa049857e0209aa7d9e616f7eb3b3b78ecfdb0 - notice how the service addresses the token using an address and not 'EOS'.