Herman Miller fiberglass - different shape?  

hi, I bought a set of upholstered Herman Miller arm shells that were office chairs. I’ve filled the holes, stripped them etc. I’m noticing though that one is a slightly different shape. The back is wider and the arms are narrower, and the seat itself seems a bit deeper.  Looking around the internet I see that there are others shaped like this and stamped with the Herman Miller logo on the bottom - but someone sanded the logo away on mine or it never had one.  Either way, what is this chair?  Still eames design?   The pics below are not my chair but the bolt holes and shape are the same.  Mine is black. This one is stamped Herman Miller on the bottom. 

https://www.ebay.com/itm/Herman-Miller-Eames-Arm-Shell-Chair-/273859848663