This small difference would very likely be several kilometers at least. As the article mentioned even the push from photons is relevant for determining the impa

This small difference would very likely be several kilometers at least. As the article mentioned even the push from photons is relevant for determining the impact site. One of these objects will be closer to the moon and will be affected more by its gravity and less by its own momentum. This effect increases with time and in the end will amount to a large difference.