The 1914 calendar (common year, starts on Thursday) repeats exactly in 1925, 1931, 1942 and beyond. Reuse an old calendar, or know when your birthday falls on the same weekday again.
Two years share an identical calendar when both start on the same day of the week and both have the same leap-year status. There are only 14 possible calendars: 7 starting weekdays × (common or leap).
A common year shifts the next year's start by 1 weekday; a leap year shifts it by 2. Common-year calendars usually return after 6 or 11 years; leap-year calendars repeat every 28 years in a pure Julian cycle (interrupted around century years like 2100 that skip the leap day).