The Grunewald company was a large musical instrument business in New Orleans founded by Louis Grunewald. By the late 1800s Rene Grunewald (son of Louis) was the head of the Grunewald factory which made mandolins,  guitars and banjos. In 1897 Rene Grunewald launched the Grunewald Harp-Guitar - first as a 10-string and then by 1902 as a 12-string double-strung  guitar.

Source; The Birth of the American 12-string Guitar. Gregg Miner. 2013