I must admit that your explanation is fascinating and , in a certain extent,maybe true , but in our case we have a constellation that tells us something else.What you saying is that the signal that we received was influenced by external factors.If we had more noise in the signal constellation would not show me .I tried the experiment described by you, but with this carrier result was the same.Spectrometer shows me the signal.
From my point of view the appearance of false signals could come to our reception facility that is not professional , for example separation of polarities is not complete , or the influence of signals from adjacent satellites.Even with these shortcomings that we have at our antennas ,we won't have never signal to the constellation.
Anyway you gave me food of thought