Clarification of Spotify data export structure

[KoreanGandalf]

The documentation of the Spotify data export has this to say about the respective json keys:

ts	This field is a timestamp indicating when the track stopped playing in UTC (Coordinated Universal Time). The order is year, month and day followed by a timestamp in military time
offline_timestamp	This field is a timestamp of when offline mode was used, if used.

However, looking at the data, it seems that often the ts value seems completely arbitrary (multiple different listens with several minutes duration have timestamps a few seconds apart, duplicate entries for the same listen have different timestamps), while the offline_timestamp value matches expectations more (same timestamp only when the song matches, different timestamps are far enough apart matching the durations).

This makes me believe that offline_timestamp is indeed the local listen time (regardless of offline mode) and ts is the time the server received the information about the listen. Could someone from Spotify's side clarify this?

Could you also clarify if there is any meaning to listens that show up multiple times in the export?

Thank you.