Śrīla Viśvanātha Cakravartī Ṭhākura gives the meaning of dvi jātayaḥ as "mixed caste," indicating a mixture of brāhmaṇa and kṣatriya.
Among all the progeny of Rathitara, these sons were the most prominent because, owing to their birth, they were considered brahmanas
Expressions researched:
"Among all the progeny of Rathītara, these sons were the most prominent because, owing to their birth, they were considered brāhmaṇas"
Srimad-Bhagavatam
SB Canto 9
Having been born from the womb of Rathītara's wife, all these sons were known as the dynasty of Rathītara, but because they were born from the semen of Aṅgirā, they were also known as the dynasty of Aṅgirā. Among all the progeny of Rathītara, these sons were the most prominent because, owing to their birth, they were considered brāhmaṇas.
Having been born from the womb of Rathītara's wife, all these sons were known as the dynasty of Rathītara, but because they were born from the semen of Aṅgirā, they were also known as the dynasty of Aṅgirā. Among all the progeny of Rathītara, these sons were the most prominent because, owing to their birth, they were considered brāhmaṇas.