Gamepad input affects multiple game instances at once, due to not needing focus.

Since Gamepad input works without needing focus (which was added in 4.9 with [Link Removed]), a Gamepad's input will also affect all instances running on the same computer.

Regression?: No
This occurs in 4.20 and has been reported that it was occurring as far back as 4.9.

1. Create a new project that takes input (ThirdPersonTemplate works)
2. Run the following command at least twice:

    UE4Editor.exe <PathToProject> -game -Windowed -ResX=640 -ResY=480 

3. Once the multiple instances of the game are up, use a gamepad (Xbox One pad was used to test) to move the character
   Result: The gamepad input affects all of the instances.
   Expected: The gamepad input only affects the focused instance.