Double door system (1) comprising an understriking door leaf (2), an overstriking door leaf (3) and a mechanical brake arrangement (100, 200, 300, 400), wherein the mechanical brake arrangement (100, 200, 300, 400) comprises a braking means (101, 102, 201, 202, 301, 302, 401, 402) arranged to brake the movement of the overstriking door leaf (3), and a first controlling means (103, 203, 303, 403) and a second controlling means (104, 204, 304, 404), which are mechanically operated, wherein the first controlling means (103, 203, 303, 403) is arranged to control the braking of the braking means (101, 102, 201, 202, 301, 302, 401, 402) in relation to the position of the understriking door leaf (2). Mechanical brake arrangement (100, 200, 300, 400) for controlling the movement of one of the door leafs of the double door system. A door operator system (10) comprising the mechanical brake arrangement (100, 200, 300, 400).