Piano or Jahn????

[P]

I am currently spending some time in Sydney, where in the CBD a new Piano building is currently under construction. However I was looking in the February issue of the Architectural Review, in which there is a picture of 3 buildings in Potsdamer Platz, Berlin, one of these is also by Piano, but the one on the far right by Jahn looks incrdibly like the Sydney Piano building. Does anyone know who had the original idea???
Yours
Poc