In that sentence, 'fruit and computer' is presented as though it is an 'A and B' expression such as 'gin and tonic' in: A pink gin is a gin and tonic regarded by some as a cocktail. 'Fruit and computer' is not such an expression.
Where the situation is in reality A is B and C is D, your sentence is saying that A is B and D. Clearly this is not the case. If you want to say that A is B and C is D using words, then you need to say: An apple is a fruit, and an Apple is a computer. If you wish, you can add the detail of John's enjoyment of them:
An apple is a fruit, and an Apple is a computer, both of which John enjoys.
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