The history is described here: The quintic mirror was constructed by Greene and Plesser as one of a few hundred mirror manifold pairs. Candelas et al. acknowledge in their article that they got the quintic mirror from Greene and Plesser.
There is an interesting quote by Brian Greene why he did not himself pursue the enumeration problem solved by Candelas et al. using the quintic duality that he and Plesser had discovered:
You can have an equation that you know is abstractly correct, but it can nevertheless be a major challenge to evaluate that equation with adequate precision to extract numbers from it. We had the equation but we didn't have the tools to leverage it into the determination of numbers. Candelas and his collaborators developed the tools to do that, which was a huge accomplishment.
The Greene and Plesser construction as it is summarized here:
http://ilorentz.org/beenakker/MO/GreenePlesser.png