copied a production site this way:
stsadm -o backup -url http://myproductionserver -filename myproductionsite.cab
create a new empty website with the administrator web on the same server using another IP port number or another server like http://testserver or http://productionserver:12345
(I’m sure you can do that with stsadm too)
then i restore the backup file
ststadm -o restore -url http://testserver -filename myproductionsite.cab -overwrite
Maybe a iisreset may be needed in between the creation or the restore.
Works great.