The Chilean cousins won their first 4-Star gold when they defeated the USA’s Phil Dalhausser and Nick Lucena 2-0 (21-15, 21-15) in the gold medal match.
Lucena and Dalhausser will also be back in action and are one of six USA teams on the entry list.
Qatar field three teams with Cherif Younousse and Ahmed Tijan aiming to repeat their performance in 2018 when they won bronze.
Doha will host its second FIVB Beach Volleyball World Tour of the 2019-2020 season with the 4-Star Katara Open, having hosted the 1-Star Aspire Beach Volleyball Cup at Al-Gharrafa Beach Complex in November.
Italy have three teams in the draw, led by Rio de Janeiro 2016 Olympic Games silver medallists Paolo Nicolai and Daniele Lupo, while 2016 Doha gold medallist Adrian Carambula will compete with Enrico Rossi.
FIVB Beach Volleyball world champion Oleg Stoyanovskiy also returns to Doha, where he and Igor Velichko won silver in 2018. He finished ninth with Viacheslav Krasilnikov in 2019, but four months on they topped the podium at the Hamburg 2019 FIVB Beach Volleyball World Championships.
The men-only tournament will run from March 9-13 at Katara Cultural Village in the north of the city. It is the second 4-Star event on the 2019-2020 calendar and the winners will leave with 800 ranking points.
Qatar has built up a strong tradition of hosting World Tour events since it hosted its first in 2014. Two more followed in 2015 and 2016, then in 2018 the tournament grew from a 3-Star tournament to a 4-Star tournament.