The location associated with the frequency comes from the local device DB for non-CAN devices, so the G3X and the GTN are deciding that this one nearby airport with that freq is what you mean vs this other airport.
On the GTR200 for example, it gets that data over the CAN bus from the G3X, so I believe it will always say the same on both screens.
IOW, nothing to worry about
Note: I have not actually seen the code for this and am just deducing from CAN data, available DBs on fly.garmin.com and experience seeing these things happen to me as well in flight.