Not being a smart Alec, but why the focus on multiple certificates? Serious question.
A Mile eater certificate of any stripe simply means you've done a lot of rides. In my mind it adds nothing to the planning and effort required to get those rides done.
Now, I recognise that mine is a subjective view and no more valid than any other member, but, enlighten me Rebelmark, why is this important to you? I ask this respectfully and with great interest in your reply.
Edit: o.k, thinking about it I can see planning a whole sequence of rides within a time window counts as a seperate and worthwhile achievement. Anything else?