This maps pretty closely to what happens in distributed systems under uncertainty.

If a system can’t tell whether something already happened, it tends to retry.

That’s fine for reads, but for side effects it creates a weird failure mode where you’re no longer dealing with “did it succeed or fail” but “did it happen once or multiple times”.

A lot of systems quietly accept “at least once” until the action is irreversible (payments, emails, etc.), and then the problem becomes very real.