I have ghosting at night through my glasses and contacts. The optician has triple-checked my eyes (quite astigmatic / myopic) and he believes it may be the fact i have naturally large pupils so my eyes cannot focus as good at night. Checked your girlfriends pupils at night so if they're large. Also tell her to focus in the dark and when she sees the ghosting, switch a light on. If the ghosting disappears then i would say its her pupil size OR uncorrected astigmatism
Please note i am not a professional