Yeah, it's just a straight up copy of the original install and no, I can't for the life of me understand what the point is. You can edit some of the xml/txt files and gain access to the US servers with a EU install without having to copy everything like that though.
In the file "lp_options.xml" find the tag and edit it so that it looks like so:
<DefaulT RgnID="LP_REGION_EN_US"/>
In the file "lp_rgn.txt" make sure it says:
LP_REGION_EN_US
In the file "lp_lang.txt" make sure it says:
en_US
That's it, now you have access to the US servers on a EU install and your patcher won't be making a whole new copy of your install.
Edit:
One more thing. If you did a EU install and got the LP_REGION thingy then yes, the game uses the exe files in the LP_REGION folder. You could, theoretically delete anything outside that folder because it's all just dead weight.
Unless, of course they've changed it since I played last. This time around I just edited the xml/txt files so that the patcher didn't make that copy to begin with.