Another hint at Jean van Maele:
http://www.littlegun.be/arme%20belge/artisans%20identifies%20t%20w/a%20van%20maele%20jean%20gb.htm
His brevete =patent may not be related to this double rifle at all. At those times it was customary with gunmakers and retailers to brag about having invented something, related or not to the product they tried to sell .