In this verse, Maharaj Parikshit is inquiring about Balarama. How was it possible that Balarama was simultaneously in the womb of Devaki and the womb of Rohini? Whose son is he anyway, Devaki’s son or is he Rohini’s son? Generally, you cannot have two mothers but somehow, Balarama has!
Balarama first appeared in the womb of Devaki, who at one point in her dream realized that she had lost the child. At that time, it was Yogamaya who took the child and transferred the child to the womb of Rohini and therefore Balarama is known as Sankarsan – one who was attracted by two mothers and he is both the son of Devaki and Rohini. Only the Supreme Personality of Godhead can do such things.
We know well very that Balarama is non-different from Krsna. It is just that he appears in a whitish form instead of blackish but otherwise, there is no difference between Krsna and Balarama. In the famous verse panca-tattvamakam krsnam, bhakta-rupa swarupakam (Caitanya Caritamrta Adi 7.6), it is explained that Balarama is the swarupa, the original form. Balarama means “he who is very strong” or “the one who gives strength”.