how much is that doggie in the window

What's he doing? Checking out that other dog that appears at the back door at night (i.e. - his reflection). He barks and asks to go out, only to just stand or lie down on the back deck once he gets out there. He'll go in and out 10 times in a row until I finally turn off the inside light and turn on the outside light, which makes that other dog harder to see, and he finally settles down. I feel a little badly for him. It must look like the perfect dog to play with.