As you have found, a splitter will not work.
In order to ruin two 'independent' TVs you need two set top boxes each fed by an independent LNB on the dish.
Most current dishes have quad LNB and as three ports are currently in use, you need to run a cable from the spare LNB port to your 'second' set top box/TV.
You can also use a Magic Eye to connect one set top box to a second TV but the programmes will always be the same on both sets. (Try a search on satellite and Magic Eye.)
T, August 2010