Comment by stackghost
Comment by stackghost 4 hours ago
>> if you have received duplicate messages then by definition you have been delivered that message more than once
>Yes.
Okay, I'm glad we agree that delivering something multiple times and discarding the duplicates is not exactly-once delivery.
As you have described it, you are right, it's not. But presumably the thing discarding the duplicates then does something with the non-duplicates, like deliver then to something else. That is exactly-once delivery.