It seems that there are only a few of them exist. Most probably only three, although there are far more back-to-back recumbent bikes on the roads. It is a bit strange as people are more interested in recumbent tandem trikes than bikes because they are afraid of maneuverability and problems with balance. Two main reasons why there are only three or so B-2-B trikes are quite obvious, however. It is pretty complicated to design a trike like this and also to build it in needed quality and function and also it is the length of the vehicle as it is even longer than the B-2-B bike.
The picture shows an ICE version and you can read a bit more about it here. There is also a little video showing it in work.