Doubling lugs on breakers without even asking about ratings is a time-honoured tradition in Austria and Germany so I honestly don't know what FPE had to say about these. General consensus seems to be that two wires of the same size and type (solid or stranded) are reasonably safe but occasionally you see bodge jobs with up to five wires per terminal.
The colours are indeed mind-boggling to anyone, apparently most of the conductors are sleeved for some reason. The grey neutral and red earth conductors conform to the German standards of the era, as do the black, blue and black phases at the main switch. Green was an acceptable phase colour but not used in cable manufacturing, only for conduit singles.
For some strange reason there were two colour coding schemes used at the same time, one for general LV wiring and one for distribution (including low voltage up to the meter or panel). The former specified grey neutral or PEN, red earth (from 1958 onwards) and any colour for phases (although red and grey were only supposed to be used as phases where no earth or neutral was present in the same cable or conduit). The latter system specified yellow, green and purple phases and black PEN/neutral and later grey and even later blue neutrals were used, although with the introduction of blue neutrals and yellow/green earths yellow and green were no longer supposed to be used.
I think now I know what you mean by full and half-size breakers though. Is that what you've got in the bottom row to the right here?
http://inspectapedia.com/fpe/Hemm/FPEHemm09.jpgMind you, I've never seen one of these contraptions in real life (thankfully!), only on the internet!
