I have been in Taiwan for about two weeks. Some of my shopping receipts have [民国](https://en.m.wikipedia.org/wiki/Minguo_calendar) dates, some have Gregorian, and some have both. What I find confusing is that when there is both, the **day** is not always the same on both. And I have at least two receipts with the same 民国 date but the Gregorian dates differ by two or more days.