I made a very big mistake, in some instances there will be two popovers on the screen at once. What is the probability of getting my app rejected?
From the iOS Human Interface Guidelines:
Ensure that only one popover is visible onscreen at a time. You should not display more than one popover (or custom view designed to look and behave like a popover) at the same time. In particular, you should avoid displaying a cascade or hierarchy of popovers simultaneously, in which one popover emerges from another.
Apple will reject any application that displays two distinct UIPopoverControllers onscreen at once (many people I know have run into this). At first, they let a few applications on the store that did cascading popovers (a popover within a popover), but this language seems to have tightened up, so I'd expect them to not allow this now.