Resident Fees

Finland ATM 12.2 sent to Luxembourg for post resident on 9th March. There is another Bluxembourg ATM affixed, value is 14$, cancel on 27th March. The postage 14$ was just for domestic letter.
I guess there are two reason that Luxembourg ATM on it,
1, The addressee pay 14$ for post resident fees when he go to post office to pick up the letter, post office affix the ATM and cancel for apporving that cost.
2, When addressee got the letter from Finland, he affix the Luxembourg ATM and resend it again.

France ATM Nr. 9 sent to Belgium on 25th Aug for post resident. There is postage meter on it with date 5th Sep.

If you know the story which addtional local postage on the letter, please just share with us.