CDJ 400 issues and setup

Not sure if this has been asked before, I only downloaded mixxx yesterday evening on the hope I could use my pair of cdj400’s with my laptop. I’ve plugged everything in as you would and the cdj’s were identified on the drop down list. I selected them and tried to play, however the left cdj controls the left deck on the screen, but the right cdj also controls the left deck on screen. Should I be selecting something on the setup preferences to identify that they are two separate units and allocate them to deck 1 and deck 2 ?

Just speculating as I don’t own those players myself… But this is the normal way to set up. Each of your player needs to understand which deck it represents.

In your players control mode settings you would assign the decks accordingly. Set the left player to deck 1 and the right player to deck 2.

which Mixxx version do you run?

there’s no official mapping for the cdj400, which mapping are you using?
for a pair of CDJ350 for example there are two mappings in Mixxx: a … CH1 and … CH2 version, and you’d select the appropriate mapping for each side.
with some editing you can of course add channel 3 and 4.

Running the latest Windows version 32bit. It did allow me to select a preset HID mapping option and I did notice that when I selected it for both cdj’s, the file name was exactly the same.