Why an object closer to us appears in doubles when we focus at an object far away?

When you look at the further object, the nearer one appears double. The reason is that the nearer object appears to the left of the farther object when viewed by your left eye, and to the right from your right eye. When you focus on the nearer finger, a double image of the farther object forms, one to the left and one to the right of the center. The reason that they are half- transparent is that you are only seeing each out of one of your eyes.