It is certainly no coincidence that we find this type of profile in a Gautrot-Marquet instrument. Gautrot, as one of Sax's fiercest competitors, had breached the 1846 patent and Sax sued him for that in 1856. The «Cour de Cassation» finally decided in july 1859 that Gautrot was in fault. Obviously Gautrot had data on Sax's instruments, but data which refered to the first generation of saxophones only.
Sources differ as for which period the name Gautrot-Marquet was held. One source reports that the name Gautrot-Marquet was used for an affiliation around 1863 while according to the Horniman Museum the name was held for the brief period from 1875 till 1877. The firm's trade name was changed to Gautrot aîné-Durand & Cie. in 1877. In 1883 Couesnon was successor to the firm. Finally, the name of Gautrot was deleted from the company name in 1888. That makes the date of production of this instrument rather uncertain and, if the first option is valid, it might well be that it is a remnant of that period when the 1846 patent was still in force and Gautrot made saxophones illegally – around 1856.