At the time of Krishna's birth, he had been smuggled into Gokul in secret by his father intent on saving him from the murderous hands of his maternal uncle Kamsa who he was destined to kill. Krishna grew up in Gokul amongst simple folk. Then, duty called. He was summoned to Mathura. He killed Kamsa and liberated the Yadavas from his tyranny.😃
In the case of BMTD, Sagar is the krishna who is being swapped with another baby😃, so that he is safe from the murderous hands of Sin😳. Krishna grew up in Gokul and Sagar will grow up in Banaras. When the time comes he will take the revenge from sindooraa, Vidya is going to be his Radha😳😳