Neither organisation knew about the other's visits until later, and a ministry document from May last year said ERO was about to give the service a good review.
It said the ministry was at that time drafting a suspension notice and the documents showed it later downgraded one of the service's four licences to a probationary licence.
The ministry told RNZ its special squad targeting suspect early childhood services had permanently shut down two services that previously received positive reports from the review office.
Early Childhood Council chief executive Peter Reynolds said a disconnect between the review office and the ministry had been a long-standing problem.
"It has certainly been a significant issue in the past, where ERO have come in and said 'everything looks pretty good from our perspective' and a week later the ministry come in and say, 'oh no, you've got a major issue here with health and safety or with your paperwork or whatever'. So getting the consistent view has been really important," Reynolds said.
He said the sector had been assured the two organisations would try to work more closely together.
"But we would ask the question why there's a need for both agencies to be involved in this space as opposed to giving some resource to the agency that has the mandate to do the job and just letting them get on with it," he said.
"Whether it's the ministry that wants to come trotting in the door or whether it's ERO, I think that issue needs to be addressed," Reynolds said.
Early childhood advocate Susan Bates said ERO often missed serious problems in early childhood centres.
"You won't have to go far to talk to teachers and get a roomful of them who have seen this themselves. They've see centres cleared by ERO that are just not up to scratch in a number of areas," she said.
Bates said teachers were too afraid to tell the ministry or the review office about the problems they saw in early childhood services.
"It can cost them their jobs and reputation in the sector and there is no-one protecting them at the moment," she said.
Early childhood researcher Sarah Alexander said she compared review office and Education Ministry judgements on early childhood services several years ago and found a big disconnect.
"It points to the need for the Ministry of Education to be doing regular monitoring of all early childhood services and not leaving it to ERO to do their checks because they might only go in every three or perhaps five years," she said.
The ERO did not explain if its initial finding regarding the early childhood service was mistaken.
Its director of review and improvement services (northern) Steve Tanner, said the reports were withdrawn after the office learned of the ministry's investigation.
He said the public could have confidence in ERO reviews.
"We are close to finalising a protocol with the ministry to improve coordination of our different review processes and, during the second half of 2019, ERO put in place a new assurance audit process for new services or services returning to a full licence from a provisional licence," he said.
A deputy secretary at the ministry, Katrina Casey, said only four of the licences its specialist Provider Assessment Group (PAG) cancelled in recent years had been the subject of prior ERO reviews and of those, two had received three-year returns from ERO and two had received 1-2 year returns.
Casey said the ministry's enforcement role was focused on regulatory standards and funding rules, while ERO was responsible for reviewing and reporting on performance.
"The main difference in our monitoring functions is that the ministry's role supports 'enforcement powers' related to meeting licensing criteria, regulations and funding rules.
"ERO's role is focused on 'evaluation for improvement and reporting' on individual service and overall sector performance, however they have no enforcement powers," she said.
-RNZ
