Well, first make sure you follow process of disabling Use Single Process, making sure Editor Multiplayer Mode is set to Play Offline, and then enabling Use Single Process again. You shouldn’t be able to get 2 windows during Standalone anymore, so that eliminates first problem.
Then, in UE4Editor.exe shortcut, add location of the .uproject file to end of Target field (which will already be populated by location of editor.exe). It looks like you may be missing a step in there. For me, I added:
“C:\Users.\Documents\Unreal Projects\MultiplayerShootout2\MultiplayerShootout2.uproject” -game
It looks like you might be missing folder for MultiplayerShootout. Additionally, make sure there’s a space between the .uproject location and “-game”. I think for you, it would look like:
“C:\Program Files\Unreal Engine\4.8\Engine\Binaries\Win64\UE4Editor.exe” “C:\Users\DJINSERT\Documents\Unreal Projects\MultiplayerShootout 4.8\MultiplayerShootout 4.8.uproject” -game