MBP not detecting external monitor

I have 2 MBP. A private (late-2013) and a work (mid-2012). My private MBP can detect the external monitors instantly without any issues. My work MBP can only detect one of the monitors..

The monitors are exactly the same (Fujitsu Thor) and I use a mini-DP -> DP cable.

I've tried resetting PRAM and SMC.