Can the same person be referred twice?

Referral schemes are retailer specific - this means you cannot refer someone at the same retailer multiple times. However a person can be referred multiple times with the same Caffe Nero account

n short, this means that you can refer friends at several retailers within the Yoyo app or you can refer friends to another Yoyo-powered app

Note that Yoyo Wallet powers the Caffè Nero app.