Screen mirrored in main screen

[Darren Tickle]

Hi.
On my main screen I have a mirrored second screen taking up 1/4ish of the screen . Display is set to single screen . I cant move it or close it . To use whats behind it I have to look at the small copy display and look at its curser to see where main curser is but you can click in the small window only on the main window

 

[Trouble]

Hello and welcome to the forum.
Haven't seen this one before.

It almost looks like a remote desktop session that is sharing it's own desktop, or....
more likely
Something along the lines of one of many third party programs that support something called "virtual desktops"
There is also the native "Task View" button, on the taskbar lower left just to the right of the Cortana Search text box.
You might try toggling that to see if you have a second desktop configured and for some reason your current GPU and or Display isn't handling it properly and displaying it as an overlay rather than an actual virtual desktop.

NOTE: I don't have a lot of experience with these virtual desktop applications, especially the third party product of which there are many, but.....
Generally they work full size but I'm sure there are probably some that support multiple virtual desktops on a single display, although I would think that they would have easily accessible controls for switching and or turning them on and off.