there's no absolute truth in life and there's no absolute truth in FMC!
There are several aircraft positions simultaneously (sounds like quantisic mechanic !):
IRS, GPS, DME_DME etc....
The FMC will determine the most probable one using Kalman filtering I guess.
In normal life the best position is GPS or if not available DME-DME.
The bearing and range shown have purely academic interest in real life...