Here's two attachments.
Full Screen is just one monitor as it shows (so scaled 150%).
The second screen the same monitor is when I do the regselect using minicap and the shift-prtscr with Screenshot Captor.
(I did a printscreen and cropped out the extra monitor both times)

I've always used MiniCap (v 1.40.01) with the following switches:

MiniCap.exe -captureregselect -clipimage -exit

I start it using a hotkey, I select what I want to capture, and it saves to my clipboard, and it exits. Short and sweet.

However, I recently got a new monitor with a very high resolution: 3840x2160
In order to keep things readable, that monitor is scaling to 150%.
Now, when I use the switch -captureregselect, the screen changes resolution, even on my second monitor that is not scaled (ie: 100%). It changes right back after I finish the selection.
When I use -captureredregselect the resolution doesn't change.

How do I fix this?