Do you have multiple calendars selected? open your calendar app and the bottom middle tap on Calendars. This will bring a list of the calendars that are currently showing in the app. Tap on the ones you don't want to show. You'll find that at least one of them will probably only contain the public holiday info and so could be got rid of.
Maybe some of the others also have this info integrated and that can be turned off but you'll get an idea of where the calendar has originated by the names in the list so you can go to that place (Google for instance) and remove the info there and it should no longer appear on you iPad.
With iOS 7.1, Apple included a subscribed U.S. Holidays calendar that cannot be unsubscribe day this time, however, you can uncheck it or the one you currently have to remove the duplicate entries.