Ich have Traktor pro 4 and two X1 Mk3. It must be possible to control all four decks with the two controllers, isn't it?
Yes, this is possible. After startup of your X1 units you can select which decks it should control on each of it.
You can download the user manual on this page:
https://www.native-instruments.com/en/products/traktor/dj-controllers/traktor-x1/downloads/
It will give you instructions on how to set up and configure your X1s.
If you want some workarounds for the original mapping's limitations and some additional functionality at a later date, have a look at the link in my signature to access the community performance mod. But get acclimated to the controller and the software first, as it may be a lot to digest already.
