It's an extra precaution: it guarantees that the people who are doing the implementation never see the original copyrighted work, so copying is impossible. If

It's an extra precaution: it guarantees that the people who are doing the implementation never see the original copyrighted work, so copying is impossible. If the same person reviews the product being cloned, writes a spec, has it reviewed, and does the implementation, the other side can argue that knowledge that was not in the spec was used in the development. They might or might not succeed in this argument, but cautious companies firewall off those who have seen the original product and those who develop the clone, especially if the competing company has a litigious reputation.