But it would be wrong to consider them as "signals" ...
Interferometry has nothing to do with it, IMHO
Sorry, I was referring to the 4 other signals, which carry the same data stream as the main one. If you remove the differential Doppler and take into account that the frequencies were measured over a period of about 30 minutes, they seem to be at multiples of 500kHz from the main carrier.
Unfortunately we don't have any information from the operators so you may be right on the cause of the 65kHz sub-carrier's odd harmonics.