I checked what was written on some of the main green eating Thai mangoes in my area and 3 of them are very similar and they are,
Lin Ngo Hou
Origin
Thailand
Synonyms
Cobra Tongue
Fruit description
Lin Ngo Hou is dark green and has a strong bittersweet flavour when eaten green. The fruit is thin with a distinctive elongated 'S' shape and polyembryonic seed.
Comments
Similar in shape to the Cedar Bay variety.
Nan Klangwan
Origin
Thailand
Synonyms
Elephants tusk, Nang Klang Wan, Nangsangwon, MG 184, Nga Chan, Nuwun Chan, Hong Xiang, Ya-9
Fruit description
Nan Klangwan is an elongated green fruit with a curved, tapering tip and polyembryonic seed. The fruit has an average weight of 300 g with a mild flavour. Nan Klangwan is a medium-to-large tree with a dense, spreading canopy.
Comments
Nan Klangwan is exported to Japan from Thailand. This variety is grown widely throughout East Asia; hence the many synonyms. Nan Klangwan is also eaten ripe.
Cedar Bay
Origin
South East Asia
Synonyms
Raboul, Golek, New Guinea long, Foo Fat, Ma 162
Fruit description
Cedar Bay is an elongated green fruit with a polyembryonic seed. Fruit can be quite large, weighing up to 800 g, with an average weight of 490 g.
Comments
This variety, or types very similar to it, are grown in many Asian countries and consumed as green eating fruit.
Pim Sane Mun
Origin
Thailand
Fruit description
This variety is green with no blush. It is elongated in shape.
Comments
Mun means Fatty. This cultivar has one of the strongest nutty flavours of the green eating types. Pim Sane Mun tends to produce many nubbins in the cooler growing regions. In Thailand, the nubbins are sold in the local markets as seedless mangoes.
I was mistaken about Cedar Bay/Rabaul being the same thing as the variety in question.