The invention relates to a method for forming a prosthetic base knit (1) made of two parallel sheets of porous knits, namely a first sheet (2) of porous knit and a second sheet of porous knit, said two parallel sheets being joined together in a discrete manner by a plurality of connecting porous knits (4) spaced apart from each other. The invention further relates to a method for manufacturing H-shaped prostheses for hernia repair from said base knit thus obtained and to the prostheses obtained therefrom.