Some ideas:

1. Did you try logging the requests and see if they're duplicated as a whole? -> that would point to some server/deployment misconfiguration. If it's just the events, most likely it's your code. You said that no duplicate requests are hitting the server. But would Laravel logs show any duplicates?
2. Did you try logging the stack trace in the event constructor? That would clarify what triggers these events down the stack and if it's the same flow. Given it's all processed synchronously that should help.
3. Do you have any switches that disable any events where !app->environment('production') or similar? Have you tried running the app on your local with the APP_ENV=Prod .env settings to imitate prod?
4. Clockwork is a good tool to trace your API requests and figure out what events are being launched, that might shed some light on the request.

Good luck!