A pressure regulator for gas distribution systems includes: a connection body for connection between an upstream pipe and a downstream pipe, the following elements being defined inside the connection body: an inlet duct an outlet duct, a high-pressure chamber connected to the inlet duct, a low-pressure chamber connected to the outlet duct, a passage opening between the high-pressure chamber and the low-pressure chamber, a movable shutter designed to obstruct the passage opening, components for moving the movable shutter in a controlled manner. The components for moving the movable shutter in a controlled manner include: a first main control head fixed to the connection body and configured to operate the movable shutter through a first control rod, a second auxiliary control head configured to operate the movable shutter through a second control rod fixed to the same movable shutter.