>>1544479>>1544619Yes, only one car was used. Even if you were able to open the doors on the rear car, there would be no platform on that side.
These setups were mostly used for temporary shuttle lines during construction works. Except Halle, which was regularly operating a line with a stub terminus, so they put the most effort into building themselves bidirectional Tatras. They also fully went back to purchasing actual bidirectional trains after 1990.
pic: a more recent example of back-to-back trams in Plauen using Tatra KT4s