Originally Posted by dc/dc
It sounds as though your lost device was never wiped and they simply inserted a new SIM and kept using it.
Your friend needs to edit your contact details to ensure that they only have your current device's PIN.
Actually the first day I checked that with some contacts and the others persons just have my new PIN and not the older one.
Confirmed right now with the other person, it only show my new one.
NOTE: Sent you a private message with the printscreen of the two phones conversation. One showing the phrase and mine where there is no register of been that phrase sent.