I'm not sure if this is a bug, but I believe it is. I got a 2x the next reward, then opened up the reveal 2 reward. Game only revealed 2 unopened presents instead of 4.
I didn't even pay attention to the stars portion, doubling that makes the pill a bit easier to swallow.It doubles the stars you get from the show two, but that's it. I posted about this on beta recently and one of the developers said that's how it's supposed to work. So I don't think they have any plans to change it to reveal 4, or have it carry over to the next prize - as I also suggested.