If both the public holidays built into Smart Planner and a Google Calendar holiday calendar (such as "Holidays in Japan") are shown, holidays appear twice.
Please turn off one of them.
- To turn off the built-in holidays: in the settings screen, tap "Calendar Settings" and turn off "Show Public Holidays"
- To turn off the Google Calendar holiday calendar: in the settings screen, tap "Calendar Settings" → "Visible Calendars" and uncheck the holiday calendar