If my hunch is right, Dish is no longer making any more Dish500's. All new dishes being made are Dish1000. They are also no longer making standard non+plus DishPro twins.
When the current Dish500 inventory is gone, they will no longer be available, as Dish300's have not been manufactured for over two years. In the same way that they have installed Dish500's with only a single lnb, they will install Dish1000's with twins only, while leaving out the 129 lnb for those installs requiring only 110 and 119.
When the current Dish500 inventory is gone, they will no longer be available, as Dish300's have not been manufactured for over two years. In the same way that they have installed Dish500's with only a single lnb, they will install Dish1000's with twins only, while leaving out the 129 lnb for those installs requiring only 110 and 119.