Yeah, she says it twice ... for no apparent reason, but I agree its likley a minor editing glitch. It's also the scene of another voice-over. The line "What can we do about him?" (as she throws the light bulb against the wall) was clearly dubbed-in later on.
She laughs at the fact that Columbo brought the burnt out bulb with him and practically scolds him in the same breath. Weird one. Susan Clark did a terrific job.