I have a similar idea like in Q:Split screen cloned display
I am sorry that I'm creating a new question then, but I'm unable to comment the answer there (I assume that because I'm new here :) ).. Anyway, my problem is, that the solution provided by Dave in topic linked above is not working on my raspberry - when I want to run the script nothing happens, it seems like script is running but there is no preview (or shall I say duplicated preview). I am 100% sure that I'm missing something or maybe it is impossible to do on monitor 19" connected via hdmi (I am very beginner in most cases of raspberry, mainly in Python things but I'm working on that). Normal fullscreen preview is working smoothly.
As I mentioned, my Raspberry Pi3 is connected to hdmi monitor, I have raspberry camera noIR connected and enabled, have Raspbian installed.
I thought that I can start with this script - just copy it to .py file and simply run it. Soon I will get 5" (also connected via hdmi) screen where I want to implement this solution - I have to add some extra code? I expected a shrinked preview on my screen :) Hope this is only my lack of knowledge...
Thanks in advance guys!