You can set scaling for each monitor in Windows 8.1. I have found that for Win32 code that looks blurry on the external monitor, I can disable scaling in the Properties of .exe in the compatibility tab.
Scaling improvements in Windows 8.1 do include setting level differently for each monitor. I assumed that is for stationary setups such as desktops. I will be docking and undocking often so what I'm asking is for the display to show only on #2 external monitor when docked with scaling automatically changing from 150% to 100%.