Marcelo,

I believe you have two different cultivars:

"Mafai-farang (Baccaurea motleyana Muell. Arg)

This fruit tree belongs to the Euphorbiaceae family, the same family as related fruits like lang-khae and mafai. Mafai-farang is a native of Sumatra, Borneo and Java. It is widely cultivated throughout Peninsular Malaysia, Sumatra, Borneo, Java and Bali, and has found its way to neighbouring countries like Thailand and the Philippines.

The English name of this fruit tree is rambai, which is also the local name for this fruit tree in Indonesia and Malaysia where it originated. In the Philippines, it is known as rambi. In Thailand, it is called mafai-farang (general), ramai, or lam-khae (Pattani), and raa-maa tee-ku (Narathiwat).

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Lang khae (Baccaurea macrophylla Muell. Arg.)

The scientific name of this fruit tree is Baccaurea macrophylla Muell. Arg. Sometimes it is also known as Baccaurea malayana King. The synonym of this species is Cheilosa malayana (Hook. f.) Corner ex Airy Shaw.

The tree belongs to the Euphorbiaceae family. Plants in this family love a humid and high rainfall climate. Lang-khae is a native of South Thailand and Malaysia, and is found distributed in Peninsular Malaysia, Singapore, Borneo, and Sumatra. It is occasionally cultivated in these areas.

There is no English name recorded for this fruit tree. Gurak gatuk (Kalimantan), bua tampoi (Sumatra) (Indonesia); tampoi, tampul, tempuni (Peninsular Malaysia); lang-khae (Thailand in general), however, there are other local names such as lam-khae (Pattani), and luk pui (Phang-nga)."

Here is a link that might be useful: Under-Utilized Tropical Fruits of Thailand

Yeah, tampoi and rambai are not the same.

In Malaysia people don't grow tampoi - it grows wild. But it can be bought at the markets. It splits into 6 segments of orange yellow fruit.

Rambai is similar to Duku and Langsat. This has fleshy fruit with bitter (green I think) seed.