How can you win "legit" by not being legit? I think you are missing the point. As soon as you open up several accounts or break the terms in one way or the other you are no longer eligable nor have any right to what might be "yours". You give up the right.
So for example, you have an account there for a long time, then you forgot the log-in credentials and can't recover it in anyway. Then you created another one, and you deposited and won a fair amount, since you broke the "multi-account" thing in the ToS, will that be enough to not let the withdraw go through?
Hhampuz is right, its just a matter of time when our fraud control department will detect multi-accounting and will suspend all accounts, especially if those accounts are created just to take advantage of promotional offers
And if found that the user didn't take advantage of promotional offer, but still guilty of having multiple accounts, you still have the right to stop withdraw because the ToS for multi-accounting is not followed.