The casino made what I assume is a promise to op that if he could own up and agree on cheating or trying to cheat the casino by operating two accounts, and also writing an apology note on a public forum like this one, that they will allow him withdraw his initial deposit and maybe winnings from slot games.
I guess in that case the casino should at least allow OP to withdraw his/her initial deposit if not the winnings. OP has broken the terms of the casinos and it will be good fate of the casino to allow withdrawal of the initial deposit. I believe most people on this forum who might operate multiple accounts on online casinos should better read the terms and conditions first and avoid creating multiple accounts.
Creating multiple accounts is of course a common practice, including in Gambling. And it is obvious that in many cases this violates the rules of using the casino. And I think that of course it would be right not to engage in such creation of multiple accounts, and even more so entire farms with different email addresses, for example, controlled by one person. If we are not talking about using bots, then such activity really takes a lot of time from the player simply because he is forced to play in one, then another, then a third account and this can also lead to confusion and in general it is all extremely inconvenient.
So it is worth thinking carefully whether you need to do this at all. Especially when your goal is only to have fun and enjoy your game.