Used stamps exchanges.

Hello,
I received NL-414 today , i say i had already received that from same member on may, but is it different code?
Kindly check

Hello,
It is possible to receive letters from the same member. New members are assigned first, and if there are no new members, then previous members will be assigned. The system will try to balance the sending/receiving of letters so that you don't send to the same members all the time.