Both HD DUO Receeivers, the 222k and the 722k (DVR), have HDMI, Composite, AND Component outputs to the main tv (TV1). Thus, you can use your current setup between the living room and the bedroom. However, if you use Component cables to connect the bedroom tv you will have a better (i.e., HD) picture!
Attached is a diagram that illustrates how to connect other tv's (TV2) that have the abliity to watch a different channel in SD than the main tv (TV1) is watching by using the Home Distribution (i.e. coax cable) output. [DUO Receiver in Dish terminology means 2 tuners in one box. That's what I love about Dish.] Thus, if you do install a second receiver, the various tv's will have the ability to watch 4 different channels!
(Note in the attached diagram that a diplexer, separator, and splitter are all quite different even though they appear to do the same thing--i.e., split / combine signals.)
Hope this helps!