instant doubles rekordbox 5.4

I have DDJ-RX and Rekordbox 5.4.0. I can only start an instant double on deck 2, 3 and 4 copying the playing track on channel 1. When for example playing a track on channel 2 and pressing instant double on channel 3 it takes the track from channel 1 although the fader of channel 1 is set to 0 and channel 2 is master. Is that normal?