I do the same from time to time, because I received definitives in one lot and I discovered I was missing some, that's why I send some myself too. You never know ...what else can you do with them??? I never send numbers, queens, kings as part of a 100 (although I have to admit that sometimes I don't know whether a stamp is a definitive or not, and a definitive from let's say Paraquay is different than the Dutch King's head, for me)