Los Dos was the name Cannondale gave to it's off-road tandems back in the early to mid-90's. They dropped Los Dos towards the end of the 90s and simply marketed their off-road tandems as the MT-800, MT-1000, MT-2000, etc...

I'm not sure there's a direct, comparative model offered by Cannondale here in the US; the Street Tandem would probably come close to an entry level Los Dos.

If you have the model year you can go to BikePedia's site and find the specs:
http://www.bikepedia.com/QuickBike/Default.aspx