Having seen your other thread and answered on there, I think its unlikely that the above represents the circuit you have a query about. I suspect whilst both sides look like they are ground when you measure them, they are in fact chassis ground and ground so one of those GND symbols should probably be CGND. The reason for such a connection would be to AC couple the CGND and GND signals on the board so they are connected for high frequency signals (such as the typical frequencies of concern for EMI) but isolated for DC.
