@ Robinson: I haven't found any way to assign 2 different LNBs to same satellite position on Enigma2. If there is a way, I don't know it.
@ Huevos: I have only one tuner. I'd normally use the fixed dish for 27,5W reception. The reason for wanting to keep the motorized dish being able to tune in to 27,5W as well is that the motorized dish is bigger so it can receive sufficient signal in inclement weather, where the fixed dish cannot. During normal weather is more comfortable to use the small fixed dish (no waiting for the motor to move the other dish)