In Black Panther, in order to be King you must consume a plant which in the comics is referred to as the Heart Shaped Herb and then "enter the ancestral plane and reconnect with the past Black Panthers."
When T'Challa consumes the plant
He meets up with his father and other past black panthers and this is not just once it happens twice once when he originally becomes King and after when he is revived in the mountains.
However when Killmonger consumes the plant
He sees his father [who is not a Black Panther] and talks to him.
Why doesn't Killmonger see previous Black Panthers if that is the point of the vision ceremony?