The news was confirmed on the Sale website on Tuesday.
Jean-Luc had an impressive spell with the club earlier this season after he joined the Sale Sharks in November last year as cover for Tom Curry, who was injured during the autumn internationals.
He made an instant impact, adding his physicality to the pack, making six appearances in total for the club - scoring one try - before returning to Durban in January.
The twins made their first-team debuts for the Sharks in 2015 and have since gone on to make over 60 appearances each for the Durban-based franchise.
The powerful back-rowers have both also represented the Springboks at senior level and offer an immense physical presence on the international stage too. Jean-Luc has been capped 13 times by his country while Daniel has made four appearances to date.
Sale Sharks Director of Rugby Steve Diamond was especially pleased to secure the services of the twins for the 2019/20 season.
"I am delighted to secure the services of both Jean-Luc and Daniel ahead of the 19/20 Premiership. Both lads are huge men with a commanding physical presence and to be able to add two world class internationals to our forward pack for next year is a huge boost for the club. I look forward to welcoming both twins to Carrington later in the year," he said.
Jean-Luc and Daniel said they couldn’t wait to return to the UK along with brother Rob.
"I’m really excited and honoured to announce that I will be joining Sale Sharks again. I really enjoyed my short stint with the club late last year, so much so that I have decided to sign another short-term contract in the UK," said Jean-Luc.
"I’ve heard some really good things about the club from Rob and Jean-Luc and can’t wait to link up with Sale in the winter and play some rugby in the Premiership with my brothers," added Dan.
It's unclear exactly how much rugby the twins will play for Sale, with Super Rugby due to conclude on July 6. The Rugby Championship kicks off a fortnight later and finishes on August 17 which in turn will be closely followed by the Rugby World Cup from September 20 to November 2.
After a short festive season break, teams will be back in training for the 2020 Super Rugby season.