Separate the application sessions first, using whatever restart evidence you actually have. Then list each source's clock basis and event ordering. A matching label across those sessions is a known ambiguity, not a connection you can safely assume.

The restart is visible in Python and the controller record. The PLC trace has no session label, and the acknowledgement carries only the reused job label.

Do not make the nearest timestamp the winner. You have evidence that the label repeats, so proximity is particularly weak evidence here.

Can the PLC owner recover a receipt sequence or another independent record, rather than something the Python application already reused?

I've asked. Their retained trace shows the signal transitions but no additional request identity. I can order events within that trace, not attach this acknowledgement to one application attempt.

That limit belongs in the report. You can retain the candidate associations and why neither is established, with the affected coupon held for the agreed reconciliation process. Do not rewrite the original timestamps to make the uncertainty disappear.

Future records need restart-safe correlation agreed across the participants, not merely a longer Python label that the receiver never returns.

Did the owner find any other evidence for this coupon, or does it remain unassigned?

No further evidence was retained. This acknowledgement remains unassigned and the coupon remains in reconciliation. The integrator is reviewing future correlation, but that will not retroactively tell us which old attempt finished.