Considering that fact that we know they reveal whats in the box I would imagine that it is the real Neal…only he and August know what Neal saw.
And as for recognizing her voice…possible…but since they made a big deal out of Emma knowing how to find someone who is hiding in that scene and later Gold tells Henry his son is adept at running it’s quite possible that Neal simple recognized the tactic of saying she had a delivery as a way to get him to open the door and catch him.
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