Twin XDJ XP1s on the same set up ?

Is there a limit to how many controllers rekordbox can handle ?

I just tried to add a second DDJ XP1 to my set up, and the first one immediately stopped working. The lights are on, but only the newer controller can now control rekordbox

My set up:

Macbook Pro (mid 2015), Mac OS Sierra, 16gb RAM

Rekordbox 5.8

1 DJM 900 Nexus 2

2 x XDJ 1000mk2

1 x DDJ WEgo

2 x DDJ XP1

If anyone has any ideas Id be really grateful