I was trying to get an XDJ-RX and an XDJRX2 to run 4 decks on rekordbox and with not much info online to help ive managed to figure it out.
My initial Problem was that Rekordbox can only have 1 midi device plugged in. So I've used Bome's MIDI translator and routed the 2 devices through 1 virtual midi port. But having 2 of the same controllers (I was using 1 XDJ-RX and 1 XDJ-RX2) they send indentical midi messages. So I made the 2nd controller deck 3/4 and now it sends different messages accross all 4 decks.
I tried to find a MIDI Mapping of the 2 controller setup but to no avail, so I reluctantly mapped out the 4 decks myself.
Here is the one i did.
https://drive.google.com/folderview?id=1ZZbLr0Yae6z-QBQoJ3Ql4qCVq-85MbYJ