Ok, I think I've figured it out. In the manual there must be a typo on page73, whereas it says:
So, in summary, 0=Say Again only, 1=Display Log only, 3=Both
I had it on
3, but the text a few lines above already suggested I should use one of these:
Setting this to...
SayAgainOp=1
...will only display the new ATC log showing the last 10 ATC commands. In
this mode you will NOT hear the normal 'Say Again' request/reply.
Setting this new option to...
SayAgain=2...will display the new ATC log showing the last 10 ATC commands PLUS you
will hear the normal 'Say Again' request/reply.
Sabre.