DOSBox/ScummVM: switching to fullscreen messes up with monitor settings

[warp-linux]

I am running Linux Mint 18.3 with Cinamon on intel graphics (4th generation core i5-4590 with
Intel® HD Graphics 4600).

I have 2 full-HD monitors in extended mode, both at 1920 x 1080 resolution.

It's working perfectly until I start an SDL-based app, like scummvm, dosbox (both installed using apt-get install...). Whenever I switch one of these apps to fullscreen using alt+enter, it goes fullscreen, but the monitor configuration is changed to clone mode, without asking me anything.

When switching back to the desktop, it stays in clone mode so I have to open the monitor preferences and set the mode to extended again.