I donīt think it is duplicate notes. I am pretty sure it is only when I play very short staccato notes...I can grab the note and make it longer in the MIDI editor then it will sound...
I have a heavy action keyboard... Triton Pro X...maybe the hardest keyboard ever built... You have to be a bodybuilder to be able to play fff on it...
So for me I can just barely come up to mf at the moment