I don't remember who told me, that I was supposed to leave one account for the bet and another to earn the income,
That's the simple solution if you want to separate balances so you don't accidentally gamble them. There's really no point us making complex changes when the same result can be so easily achieved already.
Problem is... if you have two or more accounts, you might be flagged for "Alt cheating" and both accounts might be blocked. Yes, there are steps to be taken to report both accounts... but I am not going to take that change, when I have loads of bitcoin being stored on my account to earn interest. (That 4%+)
I would rather want something to be implemented ..like a "Vault" option for the "investment" feature... so that the balance in the "Vault" would be protected from accidental gambling.
In fact, creating two balances is a good idea , one balance for the game, the other vault for getting interest, it is possible to create even a cold vault for this for greater security ,I don't know if this is possible to implement

I don’t think that two accounts are allowed, because if they were then people would use them to abuse the faucet system.
Furthermore the solution here is very simple you only need to keep the fixed amount you want to earn interest on from freebitco, and the other funds which you want to gamble, those you can deposit as and when you wish to gamble.
Alternatively you can even p make a spreadsheet or maintain an excel sheet to help you understand how much funds are available for gambling, and how much funds do you wish to keep for earning interest.