Midi merge problem

Hi I have Miditech midimerger and 3 hardware synth with keys and when I record them with mpc x it doesn't cut midi notes if I play same note twice. Anybody know why ?

this is what happen: https://www.youtube.com/watch?v=DJMNE3al06Y

Problema solved!! I cant take power to midi merger from mpc usb. When I go with power supply it records correctly !