Mirror mode decrease resolution.

To my fujitsu laptop I have connect 17" Acer via VGA and 19" Samsung via hdmi. Internal display is off. Acer and Samsung if are connected individualy works by 1280x960
but if I connect both and want mirror mode Gnome display config decrease resolution to 1024x768

What should I do to see both screen as minor at 1280x960 resolution?

I have openSUSE Leap 42.1 - Kernel \r (\l).

# inxi -F
Resuming in non X mode: xdpyinfo not found. For package install advice run: inxi --recommends
System:    Host: linux-h60s.suse Kernel: 4.1.27-27-default x86_64 (64 bit) 
           Desktop Gnome Distro: /etc/SuSE-release corrupted, use -% to override
Machine:   System: FUJITSU product: LifeBook S760 serial: R0332951 
           Mobo: FUJITSU model: FJNB20B Bios: FUJITSU // Phoenix version: Version 1.07 date: 01/26/2010
CPU:       Dual core Intel Core i5 CPU M 520 (-HT-MCP-) cache: 3072 KB flags: (lm nx sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx) 
           Clock Speeds: 1: 1199.00 MHz 2: 1199.00 MHz 3: 1199.00 MHz 4: 1199.00 MHz
Graphics:  Card: NVIDIA GT218M [GeForce 310M] 
           X.org: 1.17.2 drivers: nouveau (unloaded: fbdev,nv,vesa) tty size: 150x35 Advanced Data: N/A for root 
Audio:     Card-1: Intel 5 Series/3400 Series Chipset High Definition Audio driver: snd_hda_intel

lshw is describe at http://slymak.com/index.php?menu=lshw&source=fujitsu

thank you