> The problem now is, that I get several copies of the 
> site structure on my disk. Is there any way to do 
this 
> kind of splitting in a more intelligent way so that 
the 
> projects would be automatically joined to one site 
> structure?
Err, no. The best way if you want to mirror step by 
step, is to use the "Continue an interrupted mirror" 
feature (NOT the "Update" feature) and the "soft" 
cancel (click once to "cancel", this will finish 
pending mirrors and then stop the mirror itself)