我有 Ubuntu 19.04（不相关，我尝试过使用 ubuntu 18.04，但没有帮助）。在 Windows 中，此设置运行良好，因此不是硬件或适配器问题... 我有英特尔显卡。
我正在尝试使用 USB-C 适配器（支持双显示器设置）将 2 个屏幕连接到我的笔记本电脑。外部屏幕被镜像，并且在设置中仅显示为一个屏幕。
xrandr 输出：
Screen 0: minimum 320 x 200, current 3840 x 1080, maximum 8192 x 8192
eDP-1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 309mm x 174mm
1920x1080 60.05*+ 60.01 59.97 59.96 59.93
1680x1050 59.95 59.88
1600x1024 60.17
1400x1050 59.98
1600x900 59.99 59.94 59.95 59.82
1280x1024 60.02
1440x900 59.89
1400x900 59.96 59.88
1280x960 60.00
1440x810 60.00 59.97
1368x768 59.88 59.85
1360x768 59.80 59.96
1280x800 59.99 59.97 59.81 59.91
1152x864 60.00
1280x720 60.00 59.99 59.86 59.74
1024x768 60.04 60.00
960x720 60.00
928x696 60.05
896x672 60.01
1024x576 59.95 59.96 59.90 59.82
960x600 59.93 60.00
960x540 59.96 59.99 59.63 59.82
800x600 60.00 60.32 56.25
840x525 60.01 59.88
864x486 59.92 59.57
800x512 60.17
700x525 59.98
800x450 59.95 59.82
640x512 60.02
720x450 59.89
700x450 59.96 59.88
640x480 60.00 59.94
720x405 59.51 58.99
684x384 59.88 59.85
680x384 59.80 59.96
640x400 59.88 59.98
576x432 60.06
640x360 59.86 59.83 59.84 59.32
512x384 60.00
512x288 60.00 59.92
480x270 59.63 59.82
400x300 60.32 56.34
432x243 59.92 59.57
320x240 60.05
360x202 59.51 59.13
320x180 59.84 59.32
DP-1 connected 1920x1080+1920+0 (normal left inverted right x axis y axis) 476mm x 268mm
1920x1080 60.00*+ 60.00 59.94
1600x900 60.00
1280x1024 75.02 60.02
1152x864 75.00
1024x768 75.03 60.00
800x600 75.00 60.32
640x480 75.00 60.00 59.94
720x400 70.08
DP-2 disconnected (normal left inverted right x axis y axis)
另外，这是系统问题而不是桌面环境（gnome）但是这是我的~/.config/monitors.xml 文件内容
<monitors version="2">
<configuration>
<logicalmonitor>
<x>3840</x>
<y>0</y>
<scale>1</scale>
<monitor>
<monitorspec>
<connector>DP-1</connector>
<vendor>DEL</vendor>
<product>DELL E2218HN</product>
<serial>33G588BSDD6I</serial>
</monitorspec>
<mode>
<width>1920</width>
<height>1080</height>
<rate>60</rate>
</mode>
</monitor>
</logicalmonitor>
<logicalmonitor>
<x>0</x>
<y>0</y>
<scale>1</scale>
<primary>yes</primary>
<monitor>
<monitorspec>
<connector>eDP-1</connector>
<vendor>AUO</vendor>
<product>0x303d</product>
<serial>0x00000000</serial>
</monitorspec>
<mode>
<width>1920</width>
<height>1080</height>
<rate>60.049468994140625</rate>
</mode>
</monitor>
</logicalmonitor>
<logicalmonitor>
<x>1920</x>
<y>0</y>
<scale>1</scale>
<monitor>
<monitorspec>
<connector>DP-2</connector>
<vendor>DEL</vendor>
<product>DELL E2218HN</product>
<serial>33G588BSC0AI</serial>
</monitorspec>
<mode>
<width>1920</width>
<height>1080</height>
<rate>60</rate>
</mode>
</monitor>
</logicalmonitor>
</configuration>
<configuration>
<logicalmonitor>
<x>1920</x>
<y>0</y>
<scale>1</scale>
<monitor>
<monitorspec>
<connector>DP-1</connector>
<vendor>DEL</vendor>
<product>DELL E2218HN</product>
<serial>33G588BSC0AI</serial>
</monitorspec>
<mode>
<width>1920</width>
<height>1080</height>
<rate>59.940700531005859</rate>
</mode>
</monitor>
</logicalmonitor>
<logicalmonitor>
<x>0</x>
<y>0</y>
<scale>1</scale>
<primary>yes</primary>
<monitor>
<monitorspec>
<connector>eDP-1</connector>
<vendor>AUO</vendor>
<product>0x303d</product>
<serial>0x00000000</serial>
</monitorspec>
<mode>
<width>1920</width>
<height>1080</height>
<rate>60.049972534179688</rate>
</mode>
</monitor>
</logicalmonitor>
</configuration>
</monitors>