If you are saying plug one into the other and as soon as one is full automaticly go to the other one, I do not believe you can do that. AFAIK that can not be done, but what you can do is buy the other one, and plug it into the lacie you have now, it will mount both drives on your desktop with out wasting another port on your system. I am not sure how many times you can do this, but there is probably a limit. I have only hooked up 2 drives this way, so don't go buying 10 drives and hooking them all up, I can not gaurentee that they will all work.