Think of it this way. Each certificate becomes one UG seat. Whether it's used by the MP member who "earned" it or is otherwise gifted to someone else, it's still one seat.

If a GS/1K uses two certificates to UG self + one, both certificates have been used. While it's true that a 1K's companion could theoretically obtain an UG seat ahead of a GS, it's equally true that overall, the # of UG even out and there's no predicting whether you are a gainer or a loser.