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I have a Dell Latitude E7450 running Linux Mint running Mate and I'm using a Dell E-Port II (Model PRO3X) docking station. I'm connecting two external monitors, one via DVI and the other using Display Port, for a total of three displays. I can't get the external monitors to be independent and they are mirroring each other. I have no issues with the laptop's display itself.

I've tried the proprietary driver and that didn't seem to help. In Windows 7 there is no problem.

This is the output of xrandr, which shows the dvi and displayport as "DP1", regardless if one or both are plugged in. I can't get all three to show up when using the docking station.

Screen 0: minimum 320 x 200, current 3520 x 1080, maximum 32767 x 32767
eDP1 connected primary 1600x900+0+180 (normal left inverted right x axis y axis) 309mm x 174mm
   1600x900       60.0*+   40.0  
   1440x900       59.9  
   1360x768       59.8     60.0  
   1152x864       60.0  
   1024x768       60.0  
   800x600        60.3     56.2  
   640x480        59.9  
DP1 connected 1920x1080+1600+0 (normal left inverted right x axis y axis) 477mm x 268mm
   1920x1080      60.0*+
   1280x1024      75.0     60.0  
   1152x864       75.0  
   1024x768       75.1     60.0  
   800x600        75.0     60.3  
   640x480        75.0     60.0  
   720x400        70.1  
HDMI1 disconnected (normal left inverted right x axis y axis)
DP2 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)
VIRTUAL1 disconnected (normal left inverted right x axis y axis)

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Given the xrandr output, it seems two monitors have been recognized, eDP1 and DP1. So perhaps try telling xrandr their orientation so xrandr will stop the default mirroring behavior, by one of these commands:

xrandr --output eDP1 --mode 1600x900 --right-of DP1

or if more appropriate to have DP1 to right of eDP1 instead:

xrandr --output DP1 --mode 1920x1080 --right-of eDP1

If doing this fixes your mirroring problem but causes your other monitor to suddenly take on the same resolution, you can fix by running xrandr --output <monitorname> --mode <desired resolution> to fix it.

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  • Thank you for the response. I've updated my question to hopefully be less confusing. I have a total of three displays, two external displays and the laptop. Both external displays show up as DP1 regardless if one or both are plugged in.
    – Zamicol
    Sep 23, 2015 at 4:16
  • I have the issue did you fix the problem
    – danarj
    Aug 20, 2019 at 20:20

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