Kem Weber Chair Variations?  

Curious about these chairs. Are they all designed by Kem Weber? The bases are always the same, but sometimes there is a round back. Sometimes there is a rectangular back. Somtimes there are two bars running down from the middle of the back, outlining the spine. Sometimes the bars flow down from the corners of the rectangle. Also, sometimes the seats are a box cushion, but in the cowhide version..the seat is flat. I'm guessing that is something that was done when these chairs were reupholstered and they were all usually box cushioned. The only variations seem to be in the seat back and where the chrome runs down from the seat back. Are these variations on the same chair made at different times? Or is one the real deal and the others knockoffs that were slightly modified? If they are variations, but all designed by Kem Weber, does anyone know what the earliest design is? Were they all made by Lloyd? 
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