Only DVRs have inputs for two runs and that's purely for dual-tuner support. You can run only one tuner if you desire and leave the 2nd input disconnected. Non-DVR DirecTV equipment only has one input and can receive all the same channels.

The "splitter" Dignan is talking about is likely a Zinwell WB68 multiswitch (if it was provided free from DirecTV). This was/is standard equipment when his 5-LNB dish was installed. It's an un-powered multiswitch as far as plugging it into the wall is concerned. However, the DirecTV receivers power the multiswitch (or the dish if you have no multiswitch). Whether the receivers can provide enough power on a long run is another matter.

On the DirecTV Ku/Ka (5-LNB) system, the most crucial part to get right is the outside run from the dish to the multiswitch. It should be as short as possible and with 3GHz quad-shielded RG6 cable only. The inside wiring should be the same ideally, but RG59 was likely used when building the house because cable TV was what they had in mind... not DirecTV specs developed 15 years in the future.

At this point, I think your best bet is to scrap the multiswitch and migrate your distribution to the SWM system. Among other things, the SWM system allows dual-tuner DVR support with only a single cable run to each DVR and the inside cable can quite poor quality... as long as it's in good shape. This is possible because, unlike the traditional multiswitch system, the SWM system only sends the channels the receiver is requesting through the internal house wiring. Instead of cramming 500+ channels on a coax cable, it's only sending 1 or 2.

The downside to the SWM system is the cost associated with the equipment and the limited support for any non-MPEG4 receiver. The SWM-8 that I linked only has 3 legacy ports. This means that only 3 tuners are available to older equipment such as DirecTiVos, Hughes, RCA, Philips, or Sony branded boxes. If you have more than 3 tuners that require a legacy connection, you will need to buy (lease) new equipment that's compatible with the SWM.

SWM is natively supported by all current DirecTV boxes and DVRs starting with the HR20/H20.

I can help with install questions. Just let me know.