u2719d daisy chain problem. Display duplicate instead of extend.

@tint93  Just for additional clarity, this limitation is not related to your system.  It's specifically the dock, and likely the fact that it relies on "indirect display" technology called DisplayLink -- not to be confused with DisplayPort.  That means you're subject to limitations of the DisplayLink chipset in the dock, which don't seem to include daisy chaining based on your experience and that of someone else I recently helped here who had the same discovery.  DisplayLink incidentally comes with a variety of other drawbacks that can be significant in some use cases, which I wrote about in the post marked as the answer in this thread.  But if you're trying to run dual 1440p displays through a dock from a Latitude 5590 and you don't have Thunderbolt 3, then the D6000 is pretty much your only option.  But if you DO have Thunderbolt 3, then the WD19TBS would work and would avoid the drawbacks of DisplayLink. And it supports daisy chaining.

Thank you! So my dock is the problem... I can connect both with saperate displayport and that fixes the problem.

Do you know if i can connect another 1080p display via hdmi when i already have two 1440 connected via displayport? whem i connnect the third monitor directly to my laptop it works, but when i connect the third monitor do the D6000 it does not work. Does it have a max of 2 displays? 

@tint93  Happy to help.  The D6000 can only run triple displays when it is connected via USB-C, not USB-A "regular USB", and the system supports native GPU video output over its USB-C port, aka "DisplayPort Alt Mode".  Otherwise, it is limited to two displays because that is the max supported by the DisplayLink chipset in the dock, which does not rely on a native GPU output.  When three displays are connected, whichever display is on HDMI is driven via the native GPU output.  The Latitude 5590's USB-C port supports video output, so are you actually connecting the D6000 to that port?  If so and you still can't get the display working, try updating the D6000's firmware and then update the system's BIOS, Intel Graphics drivers, and DisplayLink software (from DisplayLink.com).

Wouw, it works now, thank you very much!