One of Vishnu's most famous incarnations is that of Vamana the dwarf. The story is told throughout Hindu scripture, as I discuss in this question. Just to refresh people's memories, the story goes roughly as follows: the Asura (demon) Mahabali, grandson of Vishnu's devotee Prahlada, took over the three worlds by conducting a hundred Ashwamedha Yagnas (horse rituals). Indra went to Vishnu for help, so Vishnu incarnated as Vamana, the youngest son of Indra's parents Kashyapa and Aditi, and then he went to Mahabali's hundredth Ashwamedha Yagna. He asked Mahabali for three steps of land, and then he grew gigantic and used those steps to take back the three worlds for Indra and the gods.
But according to Rupa Goswami, an Acharya of the Gaudiya Vaishnava sect (which the popular organization ISKCON is a part of), this isn't the first time that Vishnu has incarnated as a dwarf; here is what he says in his Laghu-Bhagavatamrita:
Lord Vamana appeared three times in this kalpa. During the reign of the first (Svayambhuva) Manu, He visited the sacrifice performed by Vaskala, the king of the danavas. Then, in the reign of Vaivasvata Manu, and visited the sacrifice performed by Dhundhu. Then, in the seventh catur-yuga of that manvantara, He appeared as the son of Kasyapa and Aditi. In this way, to accept a donation, He appeared three times as Lord Trivikrama.
The third incarnation is the famous one I discussed above. But my question is, what is the story of Vishnu's two earlier Vamana incarnations, involving Vashkala and Dhundhu? Are these described in Hindu scriptures?
Are there any commentaries on Rupa Goswami's work that shed light on this?
