It's possible to do but complicated (was for me).
It took me about a month of off and on fidgeting with my setup to figure out how to do it 100%.
I have this Dish625. A line comes from the basement to where the 625 is. In the bedroom, from the wall outlet comes a line with a
diplexer. I think the diplexer acts as a "two-way street." Connected to the connector on the diplexer labled "in/out." is the line from the basement. A short line runs from the "sat" connector to a Filter that says "sat 1" and "sat 2." which plug in accordingly on dish625 box. From the dish 625's TV2 RF output connector, I have a short line that goes to a 2-way RF splitter. The first line from the splitter travels along my upstairs to "TV2 A." The 2nd line from the splitter connects a short line to the "VGF/UHF" connector on the diplexer.
In the basement at my structured wiring box, I find the line that goes to my bedroom. Attached to this line is another diplexer's "in/out" connector. The "sat" connector has a line that runs to the dish network switch. From the "VHF/UHF" connector on the diplexer I run a short line to an In-line amplifier that I had leftover from when I had comcast. From the In-line amplifier (vhf/uhf) I have a line connected to a 4 way splitter with only 2 rooms connected to it.
So I can watch/record anything on TV1, and then I have a 2nd feed going to TV2 A, B, and C. All of the TV2s have the same picture all the time (unless watchng a DVD/Playing videogames etc), and I only have 1 TV2 remote (I plan to get another 1 or maybe 2). the Primary TV1 on this setup is in my bedroom, but I prefer to watch tv in the basement on the big screen and then we also have a guest room and a loft where I can watch TV 2. Too many tvs haha. But I prefer having the box handy in the bedroom incase something goes wrong, and just to see the status lights.
My parents have the ViP 622 box connected similarly between the family room (HDTV) and master bedroom (SD TV2 over RF), on that setup theres only one TV 2, so a diplexer is used but no splitters/amplifier.
We have a three Cat5 jacks in the kitchen, so I plan using one for TV and getting a pair of these:
and creating a TV 2 B from the Vip 622 in the family room to the kitchen's cat 5 jack. That way parents can pause live tv in bedroom, come down to the kitchen, turn on tv and play. Also, while main tv is on in family room, cnn or fox news or whatever can be on mute in the kitchen. We have a plasma in the family room and dont like to watch news there cause of the tickers. So I can do a TV 2 in the kitchen with an old computer monitor.