When you submit your application, you are agreeing that all the information is truthful to the best of your knowledge. Every application I filled out specifically asked if I have been enrolled in another professional school. Therefore, this isn't a "but they didn't ask me about it" cop out situation.
If you lie and hide this information, and that lie is the difference between you being accepted and not being accepted, then you are not actually qualified for that school based on their standards. You would be taking the place of someone who did not lie on their application and in fact is more qualified than you. There's a great chance that you won't HAVE TO lie to get into school... but would you really want to have to think about whether it was a bold-faced lie that sneaked you into school, or whether you actually deserved it?
There's a reason why they want to know that information. I think its a fair question for them to ask you how you think you'll be able to handle a similar environment the second time around when you couldn't handle it not too long ago.