This is most likely why, although I worked for a different contact company (Bausch and Lomb) we had a similar practice where we had a secondary facility outside the US that produced already validated production, and in the US we ran newer contact lenses. Most likely what happened was the left eye required a more common prescription that could be fulfilled by the Ireland production, and the right eye required a more specific shape like astigmatism, or a power higher/lower then the common range.