Calendar returns different values for 'stamp date'

there is a bug in Calendar where the value for an event’s stamp date can differ depending on how you ask for it. here’s a sample script:

tell application "Calendar"
   tell calendar id "8F70D19D-...-37151652A02D"

      set theEvents to uid of every event

      -- get stamp date from all events in one step.
      set stampDates1 to stamp date of every event

      -- get stamp date from events, one event at a time.
      set stampDates2 to {}
      repeat with e from 1 to theEvents's length
         set stampDates2's end to stamp date of event id (theEvents's item e as string)
      end repeat
   end tell
end tell

stampDates1 and stampDates2 will sometimes differ.

this bug in Calendar took me several hours to pin down!!! I have 3 apps talking to each other and I thought the problem was in my code.

Calendar was never a great scripting app. I’ve seen crashes, delays, and the ‘make new display alarm’ problem that others are seeing.

Catalina 10.15.7