As Alex marked, if ignoreDupResponses="true", the next "similar" post is sent immediately. The primary motivation is understandable - to avoid delay between the update.
However, on practice, this means that establishing Queue turn off the flooding, but ignoreDupResponses="true", turn it on back.
So, right in the upcoming release, we will change the strategy for ignoreDupResponses. It will wait until the previous post comes back and only then ignore it and send the next one.