In a Multi-stereoscopic immersive system, several users sharing the same restricted workspace, e.g. a CAVE, may need to perform independent navigation to achieve loosely coupled collaboration tasks for a complex scenario. In this context, a proper navigation paradigm should provide users both an efficient control of virtual navigation and a guarantee of users' safety in the real workspace relative to the display system and between users. In this aim, we propose several alterations of the human joystick metaphor by introducing implicit adaptive control to allow safe individual navigation for multiple users. We conducted a user study with an object-finding task in a double-stereoscopic CAVE-like system to evaluate both users' navigation performance in the virtual world and their behavior in the real workspace under different conditions. The results highlight that the improved paradigm allows two users to navigate independently despite physical system limitations.