Ghost in picture?

[milosh]

Two years ago I was with my girlfriend and we wanted to take a shot of two of us. It was evening with some street lights in the background and we placed the camera (some Olympus P&S) on a desk, since we didn't have a tripod. The image also had two "ghosts", but those two ghosts were me and my girlfriend, moved just a bit to the right and semi-transparent. Pretty scarry and puzzling. We used a long self timer, so there wasn't any movement during the exposure.