J.W. Winco offers metric linear actuators with two separate threaded shafts.

The actuators feature guide tubes of chrome plated precision steel, with metal follower nuts and plastic end caps.  The tubes are also available in stainless steel and come in a variety of diameters, and travel lengths up to 1,150 mm. Options include one shaft right hand thread and one shaft left hand thread, both shafts right hand thread, or both left hand thread.