You can do what you want with your own RR but if the package gets filled with duplicates it could mean that the only pleasure is opening the package and that is followed by the dispappointment of closing and mailing it on at some conisderable cost to the next person.

Several people advertise: send me 10 (20) (whatever) different chips and I will send you the same number of different ones in trade. I don't trade that way because I have no way of knowing whether I will get different chips or just more duplicates.

Good luck to you and have fun.