No, earmarks cannot be distributed equally, because there is no way to determine what equal is. What one person's definition of equal is, usually is not another person's definition of equal. Earmarks always go to the politicians who do the best political maneuvering, and who are the most politically powerful. Fair has nothing to do with it.
Earmarks cannot be distributed evenly simply because earmarks to each congressional district require different levels of funding. It would be nice if each project cost the same amount of money, but earmarks for a fish hatchery would be different than those for an art museum. Earmarks cost different amounts of money, so earmarks cannot be distributed equally.