A tying mechanism comprising a bill hook, twine holding device for holding strands of twines, a cutting arm adapted for cutting twines between the bill hook and the twine holding device while moving between a rest position and an extended position, a drive adapted to make the bill hook perform at least a first full rotation and a second full rotation and to move the cutting arm from the rest position to the extended position and back during a full operation cycle to form respectively a first and a second consecutive knot wherein the tying mechanism further comprises a tension regulating mechanism able to provide and regulate the tension exerted to the twine holding device during the operation of the tying mechanism.