If I understand you correctly, my setup might help you with yours. I have Cox digital cable, which means I have a set top box needed to unscramble the channels Cox includes with that package. These are the the higher numbered stations for me, but I guess that could vary depending on the cable system.
I have several Panasonic and one Magnavox dvd recorder in the room with the cable box. As was said earlier, if you use the cable box as the tuner, you have the choice of recording one station no matter how many recorders you have. And if you are going to record a scrambled station, for me something above channel 99, then you have to use the cable box as a tuner and set both it and the recorder's timers.
However, I found I also record a lot from stations that are on stations below 99, including the networks, USA, TNT, etc, so I simply split the coax feed coming from the wall into two. One I ran into the cable box. Then from the cable box I ran sound and video, using a S-video cable, to a Radio Shack signal distributor. That gave me four outputs which I then ran using a/v cables to the line inputs of the Panasonic recorders.
By doing that, I can still record only one scrambled station at a time, but I can control which machine I record on, since I like to use different units for different types of programming (sports on one machine; movies on another, that sort of thing).
The other split from the original wall coax I have going into the RF inputs of the recorders. This allows me to record DIFFERENT stations concurrently on different machines, using their tuners only, since I'm bypassing the cable box.
Finally, I also have a cheap antenna in the room that receives over the air HD signals from the networks (plus a few odd ball stations). These pictures are very good and I use that feed by splitting the signal coming in into a couple of newer Panasonic recorders with ATSC tuners, and into the Magnavox, which also has an ATSC tuner. Great picture quality.