Your Tivo needs to have two cables connected to it and then it can record two shows at the same time while you watch one of them or watch one that was already recorded.
Your DVR must have 2 tuners built-in and have 2 cables from the dish or multiswitch. DirecTV DVRs have this capability and some Dishnet DVRs also have it. What DVR do you have?
That DVR has the capability, but you must have two separate lines coming to the receiver from the satellite in order to tune multiple channels at once.
To work properly, you need two separate coax (RG6) cables coming from your satellite dish. Did you install this yourself or was it professionally installed? If it was pro-installed, it should have both cables. If the pro-installer didn't do both, call him back because it is supposed to be part of the install. That is the only way to get both tuners to work. There is no other way to record two shows or watch one/record another.