copied a production site this way: 

stsadm -o backup -url http://myproductionserver -filename

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 -overwrite 

Maybe a iisreset may be needed in between the creation or the restore. 

Works great.