Right now, I am using the following configuration to access the Tor network. My configuration uses two computers. The first computer has two network interface cards and is setup using Tor (just Tor) and privoxy. It is setup to be a (isolating?) proxy server. The second computer is setup using the the Tor bundle browser which is configured to access the Tor network using the proxy server address of the first computer. To my way of thinking, this configuration has to use two circuits through Tor. Am I correct? This configuration seems to work fine. I left out a lot of details in case there is no interest in this configuration experiment.
Yes, it does use two consecutive Tor circuits. That's generally considered to be unwise. See this Tor.SE question: Is running Tor over Tor dangerous?.
I thought that Tor clients might not connect via Tor exits. Exits are all public, and it would be easy to implement. But I just checked, and that's not the case. TBB in a CrunchBang LiveCD VM does in fact connect to a Tor entry guard via a Tor-proxy VM. And the connection isn't substantially slower than either Tor-proxy circuits or TBB circuits alone.