Two-tap identification, sometimes called double-tap, splits the till interaction into two gestures: the shopper first taps to present their wallet pass, then taps again to pay. The first tap identifies the member and lets the point of sale apply discounts, member pricing or rewards; the second tap settles the adjusted amount.
The separation is the point. Because identification and payment are distinct steps, the member can pay however they like: a different card than the phone holding the pass, cash, or a card that is not in any wallet at all. It also works on setups where the loyalty read happens on a dedicated NFC reader beside the till rather than on the payment terminal itself.
Two-tap is not a lesser version of one-tap identification. One-tap wins on speed when the terminal supports it and the member pays with the phone carrying the pass; two-tap wins whenever those conditions do not hold. A program that runs both covers every combination of hardware and payment habit.
Both flows read the pass over NFC, using Apple VAS on iPhone and Apple Watch and Google Smart Tap on Android, and a pass can also carry a QR code or barcode for tills that scan instead of tap. Identification routes are equals; the till decides, the member never has to.