It seems different to me. The difference is that your beliefs come out accurately. It's easier for people (and less complicated in general intelligences) to force beliefs they know are accurate than beliefs they know are false. I can make my hand somewhat numb by believing that my belief will make it numb through some neural pathway. I can't make it numb by believing god will make it numb. Parts of me that I can't control say "But thats not true!"
Also, if you are engaging in self deception you have to work hard to quarantine the problem and correct it after self delusion is no longer necessary. On top of that, if your official belief node is set one way, but the rest of you is set up to flip it back once omega goes away, who's to say it won't decide to ignore your Official Belief node in favor of the fact that you're ready to change it.
If you believe that you'll win a lottery, and you win, it doesn't make your belief correct. Correctness comes from lawful reasoning, not isolated events of conclusions coinciding with reality. A correct belief is one that the heuristics of truth-seeking should assign.
Here, the agent doesn't have reasons to expect that the box will likely contain money, it can't know that apart from deciding it to be so, and the deciding is performed by other heuristics. Of course, after the other heuristics have decided, truth-seeking heuristic would agree that there are ...
Omega appears to you in a puff of logic, and presents you with a closed box. "If you open this box you will find either nothing or a million dollars," Omega tells you, "and the contents will be yours to keep." "Great," you say, taking the box, "sounds like I can't lose!" "Not so fast," says Omega, "to get that possible million dollars you have to be in the right frame of mind. If you are at least 99% confident that there's a million dollars in the box, there will be. If you're less confident than that, it will be empty. I'm not predicting the state of your mind in advance this time, I'm reading it directly and teleporting the money in only if you have enough faith that it will be there. Take as long as you like."
Assume you believe Omega. Can you believe the million dollars will be there, strongly enough that it will be?