As a "mod" on a satellite forum may I add a few comments?
A dual or quad LNB is 2 or 4 independent units sharing the same feedhorn. This allows twin tuner boxes like the SKY+ to access different frequencies and signal polarities at the same time. So there is no reason why you couldn't share a dish with your neighbour. For the small price difference go for the quad. Using an "old" dish pointing at 19.2 E is also perfectly feasible. These were usually 60cm or larger, so are actually bigger than minidishes used in the same area. You will need to replace the LNB with a current "Universal" one though, or you won't get the full range of frequencies. There isn't much English Free To Air programming on that satellite position though, but the German analogue channels are moving to digital. If you want some more choice then there are 2 options: 1) multiple LNB's on one dish and 2) a motorised system. The first is only suitable for a limited range (typically no more than 15-20 degrees apart, but has the advantage of instant switching between satellites. The motorised route requires careful installation and takes time to move from one to another, but opens up a whole new world for the enthusiast.