For example, if numberOfMonths=2, and initialMonth is 'June'. Navigating through calendar with next/prev month show only pair of mounts ['June', 'July'], ['August', 'Sept'], ['Oct', 'Nov'] and etc. But not ['July', 'Aug'] or ['May', 'June'].
Try navigation at http://www.gpbl.org/react-day-picker/ Range of days example.