RM-1 Amplitude Modulation

[satyr32]

Someone who knows Amplitude Modulation knows that if a sine carrier with 100Hz is amplitude modulated with another 100Hz sine, the frequency output is 100Hz and 200Hz (and 0Hz). That is also the output if you use AM on Thor. If I do the same with RM-1 though (AM switch on), input a 100Hz sine and a 100Hz sine through the sidechain, the output is at 100Hz and something around 320Hz (instead of the expected 200Hz). Does the AM of RM-1 something different than classic AM? Or is the sidechain input thought to be for something else? I do not get it.