This is how solar-based Tong Shu Chinese Almanac work
This only happens when the solar month changes. At the end of a solar month, the calculation of Day Officers resets for the new month. Because the last solar day of the previous month may partially overlap the first day of the next solar month, the same Day Officer can appear on two consecutive civil calendar days.
Conclusion
The duplication of Day Officers on consecutive days is not an error. It only occurs at solar month transitions due to the way solar days and Day Officer sequences are calculated. Physical Tong Shu copies confirm this because they follow the same solar time calculations, not local civil time.
Warmest Regards,
