John is correct. Unscrew it & you will see. Extensions are not all equal, quality extensions have a fatter stem end that pushes on the Schrader valve & others have a thin end that slips off of the Schrader & doesn't work so well.
Jim
2014 Newell Coach 1482 Mid Entry 45'8" Valid Slides and Valid Levelling
Looks to me like it had dual connectors for single fill and thay have broken off. The scarring on the rim tells me there was a braided line in there at one time. Grab some wrenches and remove the extra parts and you'll see a normal valve stem with core underneath it. When the combination hose breaks it releases a spring inside the tube so it doesn't cause both tires to lose all air. The original valve core in the lower stem holds the pressure.
