If it's the only one of its kind on the market, it means that it's only used within your platform. Then why you choose that symbol for it? USDT usually refers to USD Tether which widely used in different exchanges. By using the same symbol, a lot of users will be confused about it and may try to withdraw it in one of the Tether supported Blockchains, so there is a risk that they may lose their balances because of this. Right ?