This is the answer :

The DPSI RV Twin version is based on the DPSI RV LDO and enables complete redundancy by using two receivers, which can be automatically switched between, at your option (depending on signal quality). This means that for the first time the entire receiver station is doubly secured. A failsafe signal of the receiver is used to switch over to the second receiver in case of a failure. Thus a total of 8 channels are completely switched over and distributed to 25 servo outputs. For the first time, ALL servos can continue to be controlled in the event of a receiver failure. The system is also suitable as a teacher-student system or as a "pilot backup". A second pilot (or "student") can take over the entire model along with all control functions using his own transmitter by means of deliberate switching (or due to an interference).

In the US this can be found in the following link :

http://www.desertaircraft.com/page.php?Page=EmcotecDPSI

I though don't have 1st hand experiance>