Hi!
Can you give us more information please? Generally, a hub contains one business key by definition, as it represents a single concept.
By “Multiple business key” do you mean that you have multiple fields that make up a single business key (e.g. a concatenation / composite key) or something else?
It could also be for example that you have a dependent child situation (similar to this thread)
What you have asked could mean many things so any further insight will be helpful 