We know that eating two Devil Fruits is incomprehensible! That was affirmed in the Manga and by Oda. The Devils that live inside the Devil Fruit client would wreck one another, and the user would die on. The Devil inside a Devil Fruit or inside the client is the thing that produces the Devil Fruit users ability. In any case, Blackbeard has the capacity control 2 diverse Devil Fruits and he is the first and only one to do that.
I don’t beliee that each any character or D. character (e.g. Luffy) can eat different Devil Fruits. Along these lines, there must be another reason.
In This Video It Will Show you another Hypothesis about possible reasons why Blackbeard is able to Consume More Than One Devil Fruit.
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