I'm not from
Sadoun but I can pretty much tell you that the WaveFrontier dual M20R dual LNBF isn't going to work with the dish you are buying. Those WaveFrontier circular LNBFs are only going to work with the toroidal antennas that have 2 reflector surfaces.
Every time a circularly polarized signal bounces off a surface, the polarization changes. A standard dish has the signal bounce once, so the right-hand signals become left-hand signals before the LNBF sees them. With the WaveFrontier toroidal dishes, the right-hand signals bounce off the reflector and then the subreflector before hitting the LNBF. Thus the right-hand signal is again right-hand when it is received. Consequently, the voltage-selected polarization on the WaveFrontier LNBF is reversed from your "standard" Dish or DirecTV LNBF.
If you're getting a FortecStar dish for Dish, you need to get a standard dual output circular LNBF.