One is the ordinary cursor that you would get on your desktop, the other is the in-game curser.
They are both at different positions on the screen, and my mouse movement is attached to the desktop cursor, this means that if I want to click on anything, I need to move my desktop cursor, further up from whatever I want to click.
Not a massive gamebreaking bug, but it is a little annoying as the only way to get rid of it is to exit the game.
