Not actually mixed, but symmetric transmitter spurs from 1548 kHz, the upper one is on 1556.5v kHz. They wander a bit and vary in strength, sometimes almost inaudible.
Also 1413 kHz often has them around 1395 & 1431 kHz, but I did not find them last night.
Mauno Ritola, MWlist iog (2022-08-21)