I've got 2 tandems but not by choice. I'm trying to find a buyer for our '91-92 Santana Noventa. It's a great tandem, but we bought a Sovereign at the end of '02 and haven't aggressively tried to sell the Noventa, though we have advertized it off and on. In the meantime, it's a backup.
http://home.insightbb.com/~dtresenriter/noventa.html