GTFS-R Trip Updates -Trip ID not unique in updates

Hi team,

I am currently facing an issue on the GTFS-R Trip Updates for sydney trains. TripId seems to be getting changed in GTFS-R Trip Updates for a particular trip due to which I am not able to match the trip updates for a particular station due to which the delay is not able to show in our app.

Whether trip_name is unique for a particular trip on a platform for a day.

Can you let me know what is unique Identifier other than trip_id for a particular trip because I noticed that timetable_id,timetable_version_id seems to be changing in updates