I see, it was on TV, so it must be true. I'm not sure what this is, but there are two possibilities. It might simply be sitting on the floor of LM-2, instead of stowed as it would be in flight. The ascent engine housing. It sat roughly below the docking tunnel, but was cylindrical.
Prototypes do differ from production vehicles sometimes.
Another example is the Space Shuttle Enterprise, which has a different wing design than Columbia and the other production Shuttles. In the NASA footage the bell is nonexistent. It was stowed during flight, because objects in zero-g tend to float around and bump into things if not secured somewhere. NASM likely just left it somewhere convenient, since most visitors don't get to look inside anyway. It would be a very tight squeeze for a suited astronaut.