Installed second WP installation on server Media Library ERROR

Hi,

I have installed a second WordPress installation on the same serve so that I can re-design the website with any down time.

I have created a new folder, installed WordPress in that folder, creating the new website. Then planning on deleting the contents from the root website and move the contents of the new folder into the root. does this sound viable?

Media Library
The problem i’m having is that the new installation’s Media library has copied over the majority of media files abut they have not thumbnails and all have url’s to the original site.

I thought that Media Library would have been empty and i would have had to copy the folders over via FTP?

Mark