A query to find all the wheels

Cy D. Fect, looking forward to the day when he will rise in the organization, gives a query to find all the wheels (using the wheel rule of section 4.4.1):

(wheel ?who)

To his surprise, the system responds

;;; Query results:
(wheel (Warbucks Oliver))
(wheel (Bitdiddle Ben))
(wheel (Warbucks Oliver))
(wheel (Warbucks Oliver))
(wheel (Warbucks Oliver))

Why is Oliver Warbucks listed four times?

Nobody's finished this exercise yet. You'll be the first!

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