Such "split planchet" coins are considered mint errors, although anecdotal evidence suggests that for larger coins such as the 50 cents it is all too easy to "create your own" split planchets, just by throwing a few 50 cent coins against a concrete wall or floor at just the right angle.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis