Would it make sense to replicate a partition on the same drive?

Question

I'm currently getting into ZFS and read a sentence in oracles documentation which make me wonder

> A mirrored storage pool configuration requires at least two disks, preferably on separate controllers
> preferably

http://docs.oracle.com/cd/E19253-01/819-5461/gavwn/index.html

Are there any scenarios where I would create a replicate on the same disk? That doesn't make any sense to me