Two Zi Wei Dou Shu apps can produce different charts from apparently identical details. Near a lunar new year or for a leap-month birth, calendar settings may differ before any interpretation begins.
Lock the original input
Keep the recorded Gregorian date, local time and birthplace. Note whether a lunar month was a leap month. Align time zone, solar-time rule, year boundary and star-placement convention one setting at a time. Record which palaces change after each adjustment.
Preserve a reproducible result
Save the app version and settings. If both tools still disagree, compare their published calculation rules and mark unresolved assumptions as unknown. Interpret decade and annual layers only after the natal calculation has a clear basis.