Simple Map Question

[Hildar]

First off, I imainge I can figure this out when I get home and actually do the download myself. But, I am at work, and was just directed to this.

My question is this ... does the downloaded maps from here (I guess .dd files) merge / overlay with the current maps if there are any?

I mean, if I am in Thundering Stepps, do I still see SOE's map with the towers and stuff on them, or do these new maps "trump" those and only show the new maps?

Many thanks.