A further thought on the invocation and address

The invocation ascribes our book to "Saint Isidore," which to me sounds a lot like Isidore of Seville. As we've said twice now, though, Isidorus Mercator -- the name given in the address -- is definitely not Isidore of Seville, but a conflation of the Spanish encyclopedist and Marius Mercator.

So is there then some tension between the invocation and the address? Do they contradict one another?