Social Development Minister Paula Bennett says another privacy breach at Work and Income was the result of human error, not systemic failure.
A woman who went to Work and Income for a food grant received details of four other clients in her documents.
It comes a week after the discovery of a major security breach with Work and Income computer self-service kiosks where private information about clients could be readily accessed.
Mrs Bennett said on Wednesday she is not excusing the latest breach, but it has probably been highlighted because of last week's controversy.
"We have got a relatively junior office member who has made a genuine mistake. I'm not going to hang them out to dry, I'm going to turn round and say, 'It's not what we expect', but I don't think it will be happening again in a hurry - I certainly hope not."
The minister says 4500 Work and Income staff work with more than 1 million people any given year, and occasionally mistakes will be made.
But the Labour Party says the latest breach shows that the department has a cavalier approach to clients.
In Parliament on Wednesday, Social Development spokesperson Jacinda Ardern revealed a second breach of a similar nature, telling MPs that a Work and Income client was given a list of jobs to take home only to find that the papers included a document with the personal details of another Work and Income client.
Ms Ardern is calling for the current review into the Work and Income kiosks to be broadened to include the latest breaches.