[TYPO3] importing and exporting website updates (t3d)

[Frank]

Hi,

I have a main website (site1) that I have replicated via exporting t3d and 
then importing it again and giving the new site (site2) its own name. When I 
change something in site1 I make a new version of the t3d (I export site1 
again and give the t3d file the same name so as to overwrite the first one). 
But when I imported this new t3d version, while clicking on site2 root, the 
t3d gets imported as a subpage of the site2 root. And like that my site2 
structure is messed up.
Someting like:

site2 root
    site1 root
        site1 first page
        site1 second page

If I would import the new t3d while clicking on the root of my Typo3 
installation then this would produce in fact a 3rd site.
But what I want to do in fact is simply update site2 with the changes made 
in site1.

I hope this is comprehensible? Can someone help please? I didn't find a good 
tut on this theme...

Thanx,
Frank