Yes, you can open multiple ‘trading’ accounts from your Octa Account. These are trading accounts, not separate Octa accounts, meaning you can have one OctaTrader account, another MT4 account for example. But this does not mean that you can open multiple Octa accounts, this only means that under your 1 Octa account you can have multiple accounts for trading.
The benefit of having multiple accounts is that you can use these for different trading strategies. For example, you can use one account to only swing trade, and another account for intraday trading. Or you can have different accounts in different base currencies.