Well, yes, this is a common question. By default, Fedora keeps TWO kernels, just in case the new/updated one breaks something - so you have a back-up to fall back on. In fact, I think that the default is now THREE. Also, by default, the newest should boot first, unless you manually over-ride GRUB.
P.S. Personally, I set my default to keep FIVE. I like back-ups.