It is the latest development in efforts to solve the mystery of the aircraft, which went missing in March 2014.
The plane, flying from Kuala Lumpur to Beijing, had 239 people on board when it vanished.
It is presumed to have crashed into the sea after veering off course.
Three ships are searching a 120,000 sq km area of the southern Indian Ocean but have so far found no trace of the plane.
Five pieces of debris have been confirmed as definitely or probably from the plane.
Each was found thousands of miles from the search zone, though within the area models of ocean currents have indicated debris could wash up.
1. A section of wing called a flaperon, found on Reunion Island in July 2015 - confirmed as debris in September 2015
2. Horizontal stabilizer from tail section, found in Mozambique in December 2015
3. Stabilizer panel with "No Step" stencil, found in Mozambique in February 2016
4. Engine cowling bearing Rolls-Royce logo, found in March 2016 in Mossel Bay, South Africa
5. Fragment of interior door panel found in Rodrigues Island, Mauritius in March 2016
All the debris is being examined in Australia by the Australian Transport Safety Bureau (ATSB) and other experts.
They use manufacturing marks on the pieces as well as samples of marine ecology like barnacles to help confirm whether they are likely to have come from the missing Boeing 777.
Speaking on Thursday, Malaysia's Transport Minister Liow Tiong Lai said the team had "confirmed that both pieces of debris from South Africa and Rodrigues Island are almost certainly from MH370".
The ATSB also said both sections were "almost certainly" from 9M-MRO, which is the plane's registration.
No other 777 has ever crashed in the southern hemisphere, and none has reported missing pieces.
The ocean search, involving Australia, Malaysia and China, has scoured more than 105,000 sq km of seafloor so far, much of it areas which have never been explored before.
But the countries have agreed that in the absence of "credible new information" the search will end by the middle of the year.

Fishlock, 29, had been a player and assistant coach to Jo Montemurro, who has taken up a role with the club's men's team.
Her first match in charge will be the Round 11 fixture at Sydney FC on Sunday, 8 January.
Sydney are top of the table with Fishlock's side fourth.

Humberside Police said Daniel Hatfield, 52 and Matthew Higgins, 49, died "after suffering significant multiple injuries".
Their bodies were found at a house on May Street on Friday.
Two women, aged 27 and 36, and a 38-year-old man are being held in police custody.
Det Supt Matt Hutchinson said police were keen to find out more about the movements of the two men in the week before their deaths.
"We also want to speak to people who know anything about the murder or have information about people attending or leaving May Street in the week prior to the men being discovered," he said.
"It is important to re-iterate that these murders are being treated as an isolated incident, however high visibility patrols will continue in the area to provide additional reassure to the local community."
Two pieces of aircraft debris found on beaches in Mauritius and South Africa almost certainly came from Malaysia Airlines flight MH370, say Malaysian and Australian officials.
[NEXT_CONCEPT]
Wales midfielder Jess Fishlock has taken over as Melbourne City coach for the final weeks of Australia's W-League season.
[NEXT_CONCEPT]
Three people have been arrested on suspicion of murder after the bodies of two men were found in the garden of a house in Hull.