Hi
I presume you're referring to the one on eBay. I have not seen that type of Knoll label before. Then again, I haven't seen many vintage Knoll sofas. Also, the design is not the standard Florence Knoll design. Perhaps it is a variation or designed by someone else.
Edit: Just did some quick googling and the sofa appears to be a model 67A, which is a more reclined version of the standard Knoll design. Still can't comment on the label particulars, but the sofa looks to be legit.
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