118.7 is a FSS satellite 119 is a DBS satellite they operate at different frequencies and signal strengths. A FSS satellite is weaker and needs a larger dish than a DBS. You have a different problem than you think how about a description of your problem.
A combined 118.7-119º Legacy LNB has a frequency range from 11.7 to 12.7 GHz vs 12.2 to 12.7 GHz for a normal LNB, and a LO frequency of 10,750 MHz vs 11,250 MHz for a normal LNB.
They use it for FTA receivers, where they can adjust the LO frequency, but it will not work with a subscribed receiver.
You need the original DishPro LNB for 118/119.
So technically this LNB would work with an FTA receiver for both 118 and 119 BUT not both at the same time as the settings for the LNB need to be adjusted. Not that I would be using an FTA receiver to obtain signal from these birds but i'm just trying to understand the situation.
This would also be why when I try to use this LNB with a model 3100 ird it will only see 118 because I cant adjust the LNB settings to grab 119. Im on the right track here?