i dont see the signature of corbusier wich shoud be there
cassina gives in fo onpage 12 about autenticity and sinage
in the section download you find this
https://cs2cdn.haworth.com/sites/cassina.com/files/lc50_brochure_15.pdf
The IM stamp is I Maestri which includes the works of well known modernist designers produced by Cassina. Cassina furniture has a serial number stamped on the piece (the stamped signature came later), the look alikes has no serial numbers.
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